I had the same issue. When I first set up Maiana on the Pi5, SignalK was receiving GPS and AIS messages but the Maiana app wouldn't connect.
I'm not sure what I did to fix it, but it magically started working. I think I might have had to enable UART0 in the Serial app, and then delete and recreate the serial connection?
I'm not sure what I did to fix it, but it magically started working. I think I might have had to enable UART0 in the Serial app, and then delete and recreate the serial connection?