Adguard appears to block WiFi calling

[joncage]

I've got a weird one; I've had Adguard set up on a RPI5 home assistant install for a while and generally it's worked brilliantly and isn't in the way.

We recently transferred from BT internet to Airband and for some reason now if I instruct our router to point at my home assistant for primary + secondary DNS, lookups seem to work just fine but WiFi calling from our android phones is broken. Connections fail to establish, calls are awful.

If I switch back to using Airband's DNS servers:

• 185.130.156.7
• 185.214.220.7
  ..then it all works just fine.

Even disabling adguard doesn't fix the issue, only replacing those DNS enries.

If it makes a difference I have..

• Upstream DNS servers: https://dns.quad9.net/dns-query
• Parallel requests
• Fallback DNS servers
• Bootstrap servers: 9.9.9.9 and 149.112.112.112 on separate lines

Test upstreams gives me a green light.

I had a look at the adguard logs for my phone and can't see anything obviously wrong so how might I have misconfigured this?

[joncage]

Okay, a fair bit of googling later and I found that wifi calling for EE needs to resolve epdg.epc.mnc030.mcc234.pub.3gppnetwork.org and after whitelisting that address wifi calling appears to suddenly work!

No, strike that, I think I had the airband DNS settings when I ran that test

[joncage]

Sounds like this could be related to: AdguardTeam/AdguardForAndroid#2550