Printer ping works after setting up subnet router but while giving print command to esc pos printer it cannot establish print connection

[immortalsantee]

What is the issue?

I am trying to print in ESC/POS printer from a flutter app.

I am able to ping my printer ip address by ping 192.168.1.100. .100 is my printer. But when i try to give print command using 4g from flutter app from iPhone, it cannot establish a printer connection.

I cannot understand what is going wrong here. When i connect to wifi, it can give print command. but when switching back to 4g, it cannot give print command.

Any help would be appreciated.

Thanks

Steps to reproduce

• Subnet router configure as 192.168.1.0/24
• In tailscale console admin I enabled Subnet router as well.
• Now i ping to 192.168.1.100 from my mobile using network application on 4G network. It shows green signal.
• Now I try to give print command. It cannot establish connection and fails the print command.

I am this flutter library for giving print command.

Are there any recent changes that introduced the issue?

No response

OS

Linux

OS version

Ubuntu

Tailscale version

1.36.1

Other software

https://pub.dev/packages/esc_pos_printer

Bug report

BUG-ec04d8311814a2301b75f7cc27e93683ae1a715b7bdf493ce27e3fb9b6a666d9-20230301122202Z-5065d714e5dc49ce

[DentonGentry]

We see ACL evaluations that the iPhone is able to connect to the printer:

2023-02-28 10:08:58.144948066 +0000 UTC: Accept: TCP{100.121.x.y:64715 > 192.168.1.100:9100} 64 tcp ok
2023-02-28 10:11:25.767104962 +0000 UTC: Accept: TCP{100.121.x.y:64753 > 192.168.1.100:9100} 64 tcp ok
2023-02-28 10:57:48.341868968 +0000 UTC: Accept: TCP{100.121.x.y:50520 > 192.168.1.100:9100} 64 tcp ok
2023-02-28 10:57:48.342043803 +0000 UTC: Accept: TCP{100.121.x.y:50521 > 192.168.1.100:9100} 64 tcp ok

I think it is managing to get connectivity, but then something else goes wrong.

One thing to note is that the Tailscale link MTU is 1280 bytes, while Wifi is 1500 bytes. Since the iOS app is running directly on the Tailscale network it should know that and only offer an MSS of 1280 bytes, but if there is any kind of packet size setting which says 1500 it would be best to set it to 1280 instead.

[DentonGentry]

Problem believed to be MTU, please reopen if not.