RTSP video streaming issues on Android

Hello. I am trying to stream video to QGC from a block camera (a kind of smart camera with an integrated processor that supports H.264 encoding and RTSP video streaming).

I configure it to set up an RTSP video stream with H.264 encoded video with 720p resolution. When I connect to it with QGroundControl on my Windows computer, everything looks fine. When I connect to it using QGroundControl on my Android Tablet (Samsung Galxy Tab Active Pro) however, the frame rate drops to below 1Hz and a lot of error messages appear in the log complaining about frames arriving too late and being dropped:

I can connect to the same video stream with VLC on the tablet and then everything looks fine.

Do you guys have any ideas what may be the reason for this issue and how can I go about to solve it?