DNS Test upstream - Unusual behaviour

[adamgibbo]

Issue Details

• Version of AdGuard Home server:
  • v0.106.0-b.5
• How did you install AdGuard Home:
  • Install script
• If it's a router or IoT, please write device model:
  • Raspberry Pi 4 Model B
• CPU architecture:
  • AMD64
• Operating system and version:
  • Debian

Expected Behavior

When inserting DNS Server, in this case using DoH using NextDNS, then select 'Test Upstreams' AGH tests the server and gives information if successful or not.

Actual Behavior

Even though NextDNS and ADH logs requests and DoH is working, the test shows:
'Server "https://dns.nextdns.io/*retracted*/Home": could not be used, please check that you've written it correctly'

Screenshots

Additional Information

Issue does not occur using regular DNS or when using smaller links only occurs with encrypted DNS (DoH DoQ and DoT).

Not working: quic://Home-retracted.dns.nextdns.io
Working: quic://dns.nextdns.io

Not working: tls://Home-retracted.dns.nextdns.io
Working: tls://dns.nextdns.io

Not working: https://dns.nextdns.io/*retracted*/Home
Working: https://dns.nextdns.io/

[ameshkov]

Please try using https://github.com/ameshkov/dnslookup and check what error does it show.

[adamgibbo]

Appears to be no error. I saw someone in the Telegram chat today (I think) with the same issue. Perhaps an issue with DNS testing feature?

linux-arm64 → ./dnslookup google.com https://dns.nextdns.io/*retracted*/Home dnslookup v1.4.8 dnslookup result: ;; opcode: QUERY, status: NOERROR, id: 46343 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;google.com. IN A ;; ANSWER SECTION: google.com. 300 IN A 142.250.200.14

[ameshkov]

Have you tried DOT and DOQ endpoints as well?

[adamgibbo]

Yes. Weird behaviour. Added to the 'Additional information' at the bottom of OP

Queries are being answered when saving the addresses but just the "Test Upstreams" feature is broken

[adamgibbo]

If you would like a test profile I can PM you one on Telegram?

[ameshkov]

I guess that's not necessary, I can test it myself

[ameshkov]

After all, I cannot reproduce that issue.

Here's what AGH does to check the upstream - it sends a DNS query to google-public-dns-a.google.com. to checks that the response contains 8.8.8.8 and 4.4.4.4. Check that your NextDNS config does not block these.

[adamgibbo]

Yes this is it. I have other DNS servers blocked on my network. Stupid me! 🤦‍♂️