My hardware version: A3
Recently upgraded from 1.11EU to 1.21EU, and now it won't save any changes in settings like port forwarding and virtual servers. Even after a reset to factory settings. When I hit the "save" button it doesn't do anything for a few seconds, and then resets and starts the "gateway is measuring your network speed" thing. (it should display the reboot now/later page instead after saving).
So I figured 1.22EU is to blame, and wanted to go back to 1.11EU. But this seems impossible?
It uploads the firmware file normally, and shows the countdown page while it installs the new firmware, resets and measures network speed. But then when I login it's still displaying 1.21EU at the top...
So far I've tried these firmwares:
1.11EU B00 (A3)
1.11EU B02 (A1)
1.20EU B03 (Ax)
1.22 b05 (US beta)
I thought maybe it can't go to a lower revision number, but it won't accept 1.22 either... I'm going crazy, it's not bricked but it might as well be, it's useless if I can't change any configuration settings.

edit: Not sure if this is any help: But I'm only using wired connections, I've disabled wireless and DHCP for LAN as well. ISP settings are simply set to DHCP.