We made some progress on this in another post, linked below. I don’t know why this only manifests on recent versions of Android and not older versions and not on Linux with multiple WiFi interfaces. The problem appears to be routing, not some sort of firewalling. App permissions around routing could be a factor. I’m not an Android developer. With the WiFi connected to the dead-end (not internet connected) ELRS backpack and mobile data connected to the internet, the default interface is the mobile data link. It appears that the out-going UDP packets attempt to go that way. I have not traced them, but on advice I tried turning off the mobile data connection. With that default interface down, UDP routed out the WiFi correctly and QGC is fully functional. …except that it can’t pull imagery or terrain data from the internet. Once QGC is synchronized with the FC, the mobile data can be turned on. Now UDP sends fail again, but QGC can pull data from the internet. Once that is done, turn mobile data off again. This is a major PITA, but it seems to point in the direction of the problem and gives me a poor solution to survive for now.
