SOLVED: Android app goes to "choose server" when leaving home WiFi

[Venson]

Well the issue is that the connection is aborted from the view of the app and the "route" is no longer available. So from the apps perspective its a reasonable thing to do.

The whole issue goes deep into the topic what for example HTTP3/QIC does better, HTTP3/QIC does support such kinds of changes in network with a single connection but until we build upon that, its the "standard" why of doing things i would say.