In case somebody else locks themselves out of their Zyxel P-2602 web interface, here's how to re-enable it (pieced together from 4 different foreign language sites and 1 hour "wasted").
This morning I accidentally set web access to "WAN Only", so my router refused access from LAN or WAN. This router seem very buggy, btw, anybody else with the same wierd problems?
Anyway, if you manage to disable the web interface, here's how to enabled it using telnet.
1. Use putty.exe, select Telnet protocol and enter the router's IP and click open.
2. Enter your admin password, same as the one used on the web interface.
2. At the RAS> prompt, enter "sys smt on"
3. Enter "exit", and re-connect.
4. You should now see a menu. Select option 24, System Maintenance (type 24 [enter]), followed by 11, Remote Management.
5. Fix whatever you've done, there, then exit all the way out with Escape and 99 [enter] to log out.
You should now have control back.
Hope this helps someone out there...