On advice from the wiki I ordered a RT5370 WIFI dongle. Following the instructions I checked and found it on wlan0. So I have the following lines in my /etc/network/interfaces file:
iface wlan0 inet dhcp
And the correct data is in the conf file.
I can start and stop wlan0 manually using ifup and ifdown. Bela shows up in my router's device lists, and I can bring up the web interface on the relevant IPv4 address. But when I close down in good order and then cold boot, the dongle's LED doesn't light up and the interface stays down. Checking dmesg I see "IPv6: ADDRCONF (NETDEV_UP): wlan0: link is not ready"
If I connect through USB I can stop and then start wlan0 manually as before.
I'm using a recent Bela image. Does anybody know what's going on?