I did solve my problem albeit in a very hackish way.

In my case, the bug came from the http://192.168.4.1/c URL which produces incorrect HTML (the form code is weird).

When I press the “submit” button on the page to submit ssid+pass , it crashes my urad

I solved the issue by waiting long enough (until the browser times out) to finally get to see the URL generated by the form.

I noticed that the SSID and password fields were repeated twice in the URL, which crashes the urad.

I built the correct “submit” URL by hand and sent it to the rebooted URAD via ‘wget’, and it finally “took”.