OTA not working on Robotdyn D1 R2 boards

[paai]

Basic Infos

• [ x] This issue complies with the issue POLICY doc.
• [ x] I have read the documentation at readthedocs and the issue is not addressed there.
• [ x] I have tested that the issue is present in current master branch (aka latest git).
• [ x] I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: Robotdyn D1 R2
• Core Version: [latest git hash or date]
• Development Env: Arduino 1.8.15 and older
• Operating System: Kubuntu 18.04

Settings in IDE

• Module: Wemos D1 mini r2
• Flash Mode: [qio|dio|other]
• Flash Size: [4MB/1MB]
• lwip Variant: [v1.4|v2 Lower Memory|Higher Bandwidth]
• Reset Method: [ck|nodemcu]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz|160MHz]
• Upload Using: [OTA|SERIAL]
• Upload Speed: [115200|other] (serial upload only)

Problem Description

This is a problem related to the popular Robotdyn D1R2 boards.

Using the standard BasicOTA from the examples, the Robotdyn D1R2 stops OTA uploading after 25-50% when the AP is three meters away. Upload does not even start on APs that are farther away. All other wifi functions work just fine.Tested it on seven of these boards.

The same code on e.g., a Robotdyn D1 mini or LOLIN ESP32 (of course with different libraries) just works.

I also installed the esp8266 library from the Board manager (after uninstalling the github tree) and exactly the same thing happens.

What surprises me is that I can not find references to this problem on the internet, although the Robotdyn D1R2 is a very popular board.

[earlephilhower]

From your description of the same code working on other boards, this doesn't seem to be a core issue. Your best bet would be to use esp8266.com or https://gitter.im/esp8266/Arduino, or the manufacturer. Good luck!

[d-a-v]

As said in #5990 (comment) and if the issue is easily repeatable, a tcpdump trace could be helpful for #4054 and #6369. It can be done with the integrated netdump library.

[paai]

Yesterday I tried to contact support@robotdyn.com, but the mailaddress does not exist (!).

I never used tcpdump and would not know what to look for. I started "tcpdump host 192.168.178.50" on the commandline while uploading the sketch both for the failing D1R2 and the working D1-mini and captured the output, but I don't know what I am looking at. I am a bit reluctant to copy the output here, but here it is...

09:59:27.385609 IP 192.168.178.50.mdns > 224.0.0.251.mdns: 0*- [0q] 2/0/0 (Cache flush) A 192.168.178.50, (Cache flush) PTR myesp8266-bla.local. (88)
09:59:27.389386 IP 192.168.178.50.mdns > 224.0.0.251.mdns: 0*- [0q] 4/0/1 PTR _arduino._tcp.local., PTR myesp8266-bla._arduino._tcp.local., (Cache flush) SRV myesp8266-bla.local.:8266 0 0, (Cache flush) TXT "auth_upload=no" "board="ESP8266_WEMOS_D1MINI"" "ssh_upload=no" "tcp_check=no" (258)
09:59:28.394882 IP 192.168.178.50.mdns > 224.0.0.251.mdns: 0*- [0q] 2/0/0 (Cache flush) A 192.168.178.50, (Cache flush) PTR myesp8266-bla.local. (88)
09:59:28.401695 IP 192.168.178.50.mdns > 224.0.0.251.mdns: 0*- [0q] 4/0/1 PTR _arduino._tcp.local., PTR myesp8266-bla._arduino._tcp.local., (Cache flush) SRV myesp8266-bla.local.:8266 0 0, (Cache flush) TXT "auth_upload=no" "board="ESP8266_WEMOS_D1MINI"" "ssh_upload=no" "tcp_check=no" (258)
09:59:29.400917 IP 192.168.178.50.mdns > 224.0.0.251.mdns: 0*- [0q] 2/0/0 (Cache flush) A 192.168.178.50, (Cache flush) PTR myesp8266-bla.local. (88)
09:59:29.410441 IP 192.168.178.50.mdns > 224.0.0.251.mdns: 0*- [0q] 4/0/1 PTR _arduino._tcp.local., PTR myesp8266-bla._arduino._tcp.local., (Cache flush) SRV myesp8266-bla.local.:8266 0 0, (Cache flush) TXT "auth_upload=no" "board="ESP8266_WEMOS_D1MINI"" "ssh_upload=no" "tcp_check=no" (258)
09:59:41.271448 IP danzig.paijmans.local.43191 > 192.168.178.50.8266: UDP, length 48
09:59:42.403074 ARP, Request who-has danzig.paijmans.local tell 192.168.178.50, length 46
09:59:42.403102 ARP, Reply danzig.paijmans.local is-at f4:4d:30:49:3b:77 (oui Unknown), length 28
09:59:42.408801 IP 192.168.178.50.8266 > danzig.paijmans.local.43191: UDP, length 2
09:59:42.503109 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [S], seq 6509, win 2144, options [mss 536,nop,nop,sackOK], length 0
09:59:42.503155 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [S.], seq 4045840852, ack 6510, win 64240, options [mss 1460,nop,nop,sackOK], length 0
09:59:42.509244 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 1, win 2144, length 0
09:59:42.509539 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 1:537, ack 1, win 64240, length 536
09:59:42.509547 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 537:1073, ack 1, win 64240, length 536
09:59:42.509688 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 1073:1461, ack 1, win 64240, length 388
09:59:42.519072 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 537, win 2144, length 0
09:59:42.524412 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 1:4, ack 537, win 2144, length 3
09:59:42.524432 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 4, win 64237, length 0
09:59:42.524551 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 1461:1997, ack 4, win 64237, length 536
09:59:42.524562 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 1997:2533, ack 4, win 64237, length 536
09:59:42.549707 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 1997:2533, ack 4, win 64237, length 536
09:59:42.551319 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 1073, win 2144, length 0
09:59:42.554289 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 4:7, ack 1073, win 2144, length 3
09:59:42.554625 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 2533:3069, ack 7, win 64234, length 536
09:59:42.554638 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 3069:3217, ack 7, win 64234, length 148
09:59:42.587319 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 7:10, ack 1461, win 1756, length 3
09:59:42.613617 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 1997, win 2144, length 0
09:59:42.613659 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 3217:3753, ack 10, win 64231, length 536
09:59:42.622079 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 10:13, ack 1997, win 2144, length 3
09:59:42.648661 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 2533, win 2144, length 0
09:59:42.648689 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 3753:4289, ack 13, win 64228, length 536
09:59:42.653467 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 13:16, ack 2533, win 2144, length 3
09:59:42.675927 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 2533, win 2144, length 0
09:59:42.688534 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 3069, win 2144, length 0
09:59:42.688572 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 4289:4825, ack 16, win 64225, length 536
09:59:42.691031 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 16:19, ack 3069, win 2144, length 3
09:59:42.708675 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 19:22, ack 3217, win 1996, length 3
09:59:42.708722 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 22, win 64219, length 0
09:59:42.732732 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 3753, win 2144, length 0
09:59:42.732774 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 4825:5361, ack 22, win 64219, length 536
09:59:42.739990 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 22:25, ack 3753, win 2144, length 3
09:59:42.741033 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 5361:5897, ack 25, win 64216, length 536
09:59:42.829546 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 4289, win 1608, length 0
09:59:42.838817 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 4825, win 1608, length 0
09:59:42.838863 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 5897:6433, ack 25, win 64216, length 536
09:59:42.840613 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 4825, win 2144, length 0
09:59:42.840629 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 6433:6969, ack 25, win 64216, length 536
09:59:42.844741 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 25:29, ack 4825, win 2144, length 4
09:59:42.863117 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 5361, win 2144, length 0
09:59:42.863163 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 6969:7505, ack 29, win 64212, length 536
09:59:42.919812 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 29:32, ack 5361, win 2144, length 3
09:59:42.925440 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 5897, win 2144, length 0
09:59:42.925490 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 7505:8041, ack 32, win 64209, length 536
09:59:42.938832 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 32:35, ack 5897, win 2144, length 3
09:59:42.946402 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 6433, win 2144, length 0
09:59:42.946440 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 8041:8577, ack 35, win 64206, length 536
09:59:42.962516 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 35:38, ack 6433, win 2144, length 3
09:59:43.009683 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 38, win 64203, length 0
09:59:43.036472 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 6969, win 2144, length 0
09:59:43.036523 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 8577:9113, ack 38, win 64203, length 536
09:59:43.042647 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 38:41, ack 6969, win 2144, length 3
09:59:43.042749 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 41, win 64200, length 0
09:59:43.110125 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 7505, win 2144, length 0
09:59:43.110175 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 9113:9649, ack 41, win 64200, length 536
09:59:43.117068 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 41:44, ack 7505, win 2144, length 3
09:59:43.117152 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 44, win 64197, length 0
09:59:43.124939 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 8041, win 2144, length 0
09:59:43.124997 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 9649:10185, ack 44, win 64197, length 536
09:59:43.137283 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 44:47, ack 8041, win 2144, length 3
09:59:43.164907 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 8577, win 1608, length 0
09:59:43.172483 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 8577, win 2144, length 0
09:59:43.172526 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 10185:10721, ack 47, win 64194, length 536
09:59:43.175048 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 47:50, ack 8577, win 2144, length 3
09:59:43.186191 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 8577, win 2144, options [nop,nop,sack 1 {9113:9649}], length 0
09:59:43.186246 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 8577:9113, ack 50, win 64191, length 536
09:59:43.216490 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 8577, win 2144, options [nop,nop,sack 1 {9113:9649}], length 0
09:59:43.219818 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 8577, win 2144, options [nop,nop,sack 1 {9113:9649}], length 0
09:59:43.226702 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 9649, win 1608, length 0
09:59:43.226723 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 9649:10185, ack 50, win 64191, length 536
09:59:43.226733 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 10185:10721, ack 50, win 64191, length 536
09:59:43.231591 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 9649, win 2144, length 0
09:59:43.273901 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 50:54, ack 9649, win 2144, length 4
09:59:43.288496 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 10185, win 2144, length 0
09:59:43.288536 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 10721:11257, ack 54, win 64187, length 536
09:59:43.288546 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 11257:11793, ack 54, win 64187, length 536
09:59:43.304514 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 54:57, ack 10185, win 2144, length 3
09:59:43.350882 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 10721, win 2144, length 0
09:59:43.350932 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 11793:12329, ack 57, win 64184, length 536
09:59:43.350941 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 12329:12865, ack 57, win 64184, length 536
09:59:43.379894 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 57:60, ack 10721, win 2144, length 3
09:59:43.424847 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 11257, win 2144, length 0
09:59:43.424910 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 12865:13401, ack 60, win 64181, length 536
09:59:43.434703 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 60:63, ack 11257, win 2144, length 3
09:59:43.446781 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 11793, win 2144, length 0
09:59:43.446823 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 13401:13937, ack 63, win 64178, length 536
09:59:43.455115 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 63:66, ack 11793, win 2144, length 3
09:59:43.469475 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 12865, win 1072, length 0
09:59:43.480501 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 12865, win 1608, length 0
09:59:43.480546 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 13937:14473, ack 66, win 64175, length 536
09:59:43.503291 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 12865, win 2144, length 0
09:59:43.503330 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 14473:15009, ack 66, win 64175, length 536
09:59:43.521308 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 66:70, ack 12865, win 2144, length 4
09:59:43.526104 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 13401, win 2144, length 0
09:59:43.526134 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 15009:15545, ack 70, win 64171, length 536
09:59:43.533208 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 70:73, ack 13937, win 1608, length 3
09:59:43.543841 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 13937, win 2144, length 0
09:59:43.543861 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 15545:16081, ack 73, win 64168, length 536
09:59:43.549122 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 73:76, ack 13937, win 2144, length 3
09:59:43.559281 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 14473, win 2144, length 0
09:59:43.559294 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 16081:16617, ack 76, win 64165, length 536
09:59:43.560909 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 76:79, ack 14473, win 2144, length 3
09:59:43.582075 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 15009, win 2144, length 0
09:59:43.582111 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 16617:17153, ack 79, win 64162, length 536
09:59:43.623235 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 79:82, ack 15545, win 1608, length 3
09:59:43.630869 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 15545, win 2144, length 0
09:59:43.630887 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 17153:17689, ack 82, win 64159, length 536
09:59:43.731421 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 16081, win 2144, length 0
09:59:43.731479 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 17689:18225, ack 82, win 64159, length 536
09:59:43.733261 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 85:88, ack 16081, win 2144, length 3
09:59:43.733312 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 82, win 64159, options [nop,nop,sack 1 {85:88}], length 0
09:59:43.749342 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 17153, win 1072, length 0
09:59:43.759220 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 17689, win 1072, length 0
09:59:43.759293 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 18225:18749, ack 82, win 64159, options [nop,nop,sack 1 {85:88}], length 524
09:59:43.759304 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 18749:18761, ack 82, win 64159, options [nop,nop,sack 1 {85:88}], length 12
09:59:43.760810 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 17689, win 1608, length 0
09:59:43.760854 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 18761:19285, ack 82, win 64159, options [nop,nop,sack 1 {85:88}], length 524
09:59:43.760870 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 19285:19297, ack 82, win 64159, options [nop,nop,sack 1 {85:88}], length 12
09:59:43.762315 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 17689, win 2144, length 0
09:59:43.763642 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 88:92, ack 17689, win 2144, length 4
09:59:43.763694 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 82, win 64159, options [nop,nop,sack 1 {85:92}], length 0
09:59:43.787255 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 18225, win 2144, length 0
09:59:43.787306 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 19297:19821, ack 82, win 64159, options [nop,nop,sack 1 {85:92}], length 524
09:59:43.842914 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 92:95, ack 18225, win 2144, length 3
09:59:43.842954 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 82, win 64159, options [nop,nop,sack 1 {85:95}], length 0
09:59:43.855988 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 95:98, ack 18749, win 1620, length 3
09:59:43.856050 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 19821:20345, ack 82, win 64159, options [nop,nop,sack 1 {85:98}], length 524
09:59:43.890396 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 18761, win 2144, length 0
09:59:43.890444 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 20345:20369, ack 82, win 64159, options [nop,nop,sack 1 {85:98}], length 24
09:59:43.892410 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 98:100, ack 18761, win 2144, length 2
09:59:43.892455 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 82, win 64159, options [nop,nop,sack 1 {85:100}], length 0
09:59:43.905322 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 100:103, ack 19285, win 1620, length 3
09:59:43.905372 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 20369:20893, ack 82, win 64159, options [nop,nop,sack 1 {85:103}], length 524
09:59:43.908459 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 19297, win 2144, length 0
09:59:43.908505 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 20893:21417, ack 82, win 64159, options [nop,nop,sack 1 {85:103}], length 524
09:59:43.925847 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 103:105, ack 19297, win 2144, length 2
09:59:43.925896 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 82, win 64159, options [nop,nop,sack 1 {85:105}], length 0
09:59:43.934729 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 20345, win 1096, length 0
09:59:43.934777 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 21417:21441, ack 82, win 64159, options [nop,nop,sack 1 {85:105}], length 24
09:59:43.954325 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 20893, win 548, length 0
09:59:43.959306 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 21441, win 0, length 0
09:59:44.325666 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 82, win 64159, options [nop,nop,sack 1 {85:105}], length 0
09:59:44.346778 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 21441, win 0, length 0
09:59:44.854877 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 82:85, ack 21441, win 0, length 3
09:59:44.854901 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, length 0
09:59:44.856626 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 85:88, ack 21441, win 0, length 3
09:59:44.856631 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {85:88}], length 0
09:59:44.877299 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 88:92, ack 21441, win 0, length 4
09:59:44.877309 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {88:92}], length 0
09:59:44.926922 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 92:95, ack 21441, win 0, length 3
09:59:44.926934 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {92:95}], length 0
09:59:44.936836 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 95:98, ack 21441, win 0, length 3
09:59:44.936842 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {95:98}], length 0
09:59:44.944631 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 98:100, ack 21441, win 0, length 2
09:59:44.944635 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {98:100}], length 0
09:59:44.959573 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 100:103, ack 21441, win 0, length 3
09:59:44.959590 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {100:103}], length 0
09:59:44.969818 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 103:105, ack 21441, win 0, length 2
09:59:44.969836 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 105, win 64136, options [nop,nop,sack 1 {103:105}], length 0
09:59:44.980795 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 105:108, ack 21441, win 0, length 3
09:59:44.980825 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 108, win 64133, length 0
09:59:44.989289 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 21441, win 1048, length 0
09:59:44.989327 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 21441:21977, ack 108, win 64133, length 536
09:59:44.989333 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 21977:22489, ack 108, win 64133, length 512
09:59:45.050631 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 21441, win 1596, length 0
09:59:45.050672 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 22489:22513, ack 108, win 64133, length 24
09:59:45.052390 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 108:112, ack 21441, win 2144, length 4
09:59:45.052407 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 22513:23049, ack 112, win 64129, length 536
09:59:45.052410 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 23049:23585, ack 112, win 64129, length 536
09:59:45.059243 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 21977, win 2144, length 0
09:59:45.059280 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 23585:24121, ack 112, win 64129, length 536
09:59:45.063443 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 112:115, ack 21977, win 2144, length 3
09:59:45.067660 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 115:118, ack 22489, win 1632, length 3
09:59:45.067701 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 118, win 64123, length 0
09:59:45.148923 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 22513, win 2144, length 0
09:59:45.148951 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 24121:24657, ack 118, win 64123, length 536
09:59:45.183896 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 118:120, ack 22513, win 2144, length 2
09:59:45.222727 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 23049, win 2144, length 0
09:59:45.222771 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 24657:25193, ack 120, win 64121, length 536
09:59:45.236139 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 120:123, ack 23049, win 2144, length 3
09:59:45.243686 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 23585, win 2144, length 0
09:59:45.243731 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 25193:25729, ack 123, win 64118, length 536
09:59:45.292908 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 123:126, ack 23585, win 2144, length 3
09:59:45.295116 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 24121, win 2144, length 0
09:59:45.295154 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 25729:26265, ack 126, win 64115, length 536
09:59:45.296077 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 126:129, ack 24121, win 2144, length 3
09:59:45.314221 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 24657, win 2144, length 0
09:59:45.314269 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 26265:26801, ack 129, win 64112, length 536
09:59:45.324211 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 129:132, ack 24657, win 2144, length 3
09:59:45.374434 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 132, win 64109, length 0
09:59:45.377975 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 25193, win 2144, length 0
09:59:45.378019 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 26801:27337, ack 132, win 64109, length 536
09:59:45.383426 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 132:135, ack 25729, win 1608, length 3
09:59:45.383527 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 135, win 64106, length 0
09:59:45.386817 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 25729, win 2144, length 0
09:59:45.386849 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 27337:27873, ack 135, win 64106, length 536
09:59:45.388643 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 135:138, ack 26265, win 1608, length 3
09:59:45.390327 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 26265, win 2144, length 0
09:59:45.390371 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 27873:28409, ack 138, win 64103, length 536
09:59:45.392691 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 138:141, ack 26265, win 2144, length 3
09:59:45.398148 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 26801, win 2144, length 0
09:59:45.398196 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 28409:28945, ack 141, win 64100, length 536
09:59:45.400168 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 141:144, ack 26801, win 2144, length 3
09:59:45.441669 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 144, win 64097, length 0
09:59:45.449290 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 27337, win 2144, length 0
09:59:45.449343 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 28945:29481, ack 144, win 64097, length 536
09:59:45.542895 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 144:147, ack 27337, win 2144, length 3
09:59:45.579515 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 27873, win 2144, length 0
09:59:45.579548 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 29481:29993, ack 147, win 64094, length 512
09:59:45.581681 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 147:150, ack 27873, win 2144, length 3
09:59:45.609417 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 28409, win 2144, length 0
09:59:45.609463 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 29993:30529, ack 150, win 64091, length 536
09:59:45.614926 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 150:153, ack 28409, win 2144, length 3
09:59:45.644503 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 29481, win 1072, length 0
09:59:45.666526 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 29481, win 1608, length 0
09:59:45.666551 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 30529:31041, ack 153, win 64088, length 512
09:59:45.692737 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 29481, win 2144, length 0
09:59:45.692756 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 31041:31577, ack 153, win 64088, length 536
09:59:45.725159 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 153:157, ack 29481, win 2144, length 4
09:59:45.726996 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 157:160, ack 29993, win 1632, length 3
09:59:45.727059 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 160, win 64081, length 0
09:59:45.735191 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 30529, win 2144, length 0
09:59:45.735204 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [P.], seq 31577:32089, ack 160, win 64081, length 512
09:59:45.735211 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 32089:32625, ack 160, win 64081, length 536
09:59:45.762370 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [P.], seq 160:163, ack 30529, win 2144, length 3
09:59:45.821669 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], ack 163, win 64078, length 0
09:59:46.054344 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 32089:32625, ack 163, win 64078, length 536
09:59:46.501716 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:47.366922 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:49.093774 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:52.677677 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:55.734608 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [R.], seq 32625, ack 163, win 64078, length 0
09:59:55.741603 IP 192.168.178.50.62757 > danzig.paijmans.local.51449: Flags [.], ack 30529, win 2144, length 0
09:59:55.741662 IP danzig.paijmans.local.51449 > 192.168.178.50.62757: Flags [R], seq 4045871381, win 0, length 0
10:05:49.283593 ARP, Request who-has 192.168.178.50 tell paai_grashoek.paijmans.local, length 46

[d-a-v]

Thanks for this dump @paai.
What we can see is that at the end ESP is asking for retransmission from 30529, that is honoured by PC but never acknowledged by esp then PC shuts down the connection. It'll hopefully help to understand while reading between the lines of espota.py and the ArduinoOTA library.

09:59:45.609463 IP pc.51449 > esp.62757: Flags [.], seq 29993:30529, ack 150, win 64091, length 536
09:59:45.666551 IP pc.51449 > esp.62757: Flags [.], seq 30529:31041, ack 153, win 64088, length 512
09:59:45.735191 IP esp.62757 > pc.51449: Flags [.], ack 30529, win 2144, length 0
09:59:45.762370 IP esp.62757 > pc.51449: Flags [P.], seq 160:163, ack 30529, win 2144, length 3
09:59:46.501716 IP pc.51449 > esp.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:47.366922 IP pc.51449 > esp.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:49.093774 IP pc.51449 > esp.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:52.677677 IP pc.51449 > esp.62757: Flags [.], seq 30529:31041, ack 163, win 64078, length 512
09:59:55.741603 IP esp.62757 > pc.51449: Flags [.], ack 30529, win 2144, length 0

[paai]

Thank you. But I am rapidly getting out of my depth here and I don't speak python (the curly braces on the keyboard are there for a good reason!).
The bottom line seems to be that something is broken in Robotdyn D1R2 boards that cannot be easily remedied. But it is a popular board and has been around or at least four years, so it is peculiar that nobody stumbled over it before. Ah well... Thank you all for helping me.