NeoCortex97

I want to use a StromPi3 board with my lepotato board. I am using the armbian image. I used armbian-config to enable the serial ports and both show up as /dev/TTYAML0 and /dev/ttyAML6. Nonetheless I am unable to communicate on the serial ports even when connecting jumpers and a USB serial converter. I later tried to modify the divorce tree by hand. No change. Is there something else I could try to get the serial port on pins 8 and 10 working?