@Aim_eYacht A modem reset via the rear button was the first thing I tried (seems to be the recommended action after a firmware upgrade); in the initial setup, the wizard will not accept spaces or special characters in the SSID nor the password fields...
Unfortunately I did not take a backup on the previous firmware, and I'm now unable to restore my old SSID and password: no special characters or even spaces are allowed. If anyone figures out a solution please let me know!
