AUN on RaPi

I’ve got AUN working under RPCemu with RO 3.7 but I can’t get it
to work on RaPi using the RO 5.19 beta image.

In both cases I’ve set a manual IP adress in the “Internet”
setup panel and edited the AUNmap file to include a Net number
for my local IP subnet.

In the RPCemu/3.7 case the “AUN” panel shows a valid Net.Station
number which is correctly derrived from the AUNmap and last octet
of the IP address but on the Pi/5.19beta I just get 0

Anyone got any ideas what might be going on?