Telemetry radio works with laptop,but send only with android

I can run apmplanner and mission planner just fine when I plug my old 3DR radio in my linux system.
I can send/receive data.

When I plug it into 3 android devices (2 phones, 1 tablet, different versions of android),

  • andropilot can send data (change flight mode) but doesn’t receive any telemetry
  • old droidplanner can also send data (change flght modes), but doesn’t receive anything either

New droidplanner or tower fail to function because they detect no data is coming in.

BRD_SER1_RTSCTS was 2, I put it to 0 but that didn’t help.
That’s with APM::Plane 3.2

How could I debug this further?