Problem with Android App

[cfr2305]

Hello,
I have an annoying issue since I'm using Pi-Hole: The Lufthansa App on Android is not working properly. So you can start and browse through it, but If you wanna search for flights or change a booking you get this error:
Accessing the page is not possible.

The annoying part is, that I can't even get it to work, if I Disable blocking. So for my understanding, this problem has nothing to do with the blocklists, that are configured. So there must be more, that Pi-hole is blocking.

If I leave my network or change the DNS to e.g 8.8.8.8 the App is working proper again.
With the Lufthansa Website, there are no issues when using Pi-hole.

In my desperation I installed AdGuard Home, but with the same result. So Pi-hole and AdGuard are both blocking something, that interfere with this App.

Any idea what to check or another work around instead of changing the DNS server on the phone?

[rdwebdesign]

@cfr2305

The annoying part is, that I can't even get it to work, if I Disable blocking.
(...)
I installed AdGuard Home, but with the same result.

If the issue happens when blocking is disabled, then Pi-hole is not blocking anything. Something else is causing the issue.

This is also confirmed when you say a different software is causing the same issue.

Maybe the upstream DNS server configured in Pi-hole is blocking something.
Also check if your router, or a firewall rule, or some Android configuration is causing the issue.