Moitessier HAT serial connection problem

[Spikie2]

Hi there,

I am trying to get the mhat working with openplotter v3. I am running openplotter on a rpi4b with mhat. Somehow the serial connection stopped working and I cannot find why. I replaced the jumper on the board and redid all serial connection settings. And updated to serial 3.0
The mhat itself seems fine: LEDs indicate ais and gnss data coming in.

Any suggestions?

Thanks for your reply in advance!

Update: the connection seems to be working after startup but dies out after a few minutes without coming back.