android: wifi (only) always triggers "unable to connect to home assistant"

Home Assistant Android app version(s):

Android version(s): latest from Play Store - 20230908.0 Device model(s): Samsung S21 and S23 Home Assistant version: 2023.9.1 Last working Home Assistant release (if known): 6-ish months ago?

Description of problem, include YAML if issue is related to notifications:

Several months ago the Android Home Assistant app became unreliable: it works over Cellular, but at home over wifi it produces this “unable to connect to home assistant” error and demands I set it up again (which doesn’t work either). If I drop out of the app, disable Wifi, and re-enter the app, it starts working. And conversely, if I drop out, re-enable Wifi - it stops working.

I have just upgraded from my old Samsung S21 to a S23 and the problem remains - it affected both. I have also tried uninstalling the app, reinstalling - no change. And of course my homeassistant app works fine from my laptop over wifi - there is no problem. ie the “https://homeassistant.my.domain/” works at home over wifi via a web browser on the Android and laptop - but the HomeAssistant app on the Android does not.

BTW I do run my own DNS at home, so my homeassistant DNS name resolves to a 192.168 address on Wifi and it resolves to it’s Internet address over cellular - that’s the only difference I can think of between the two “network options”. Both DNS names resolve to the same, working homeassistant web server app.

I have homeassistant running in a docker behind a reverse proxy - the DNS name (internal and external) point to the same URL “value” (on wifi resolve to the 192.168 IP and remote/cellular resolving to the Internet IP).

Any ideas what’s going wrong? Ruins several phone-based triggers I have, because I have to remember to disable wifi for them to work.

Thanks!

Jason

Companion App Logs:

Screenshot or video of problem:

Additional information: