If you turned off your DHCP server follow these steps to connect to
FritzBox settings.

-   Set your computer IP to `169.254.1.2` and your mask to `255.255.0.0`
-   Then go to `169.254.1.1`, login and re-enable the DHCP server.

On gnome turn the wired connection off on again to apply the settings.

Note: why in the hell does FritzBox 7490 require a land-line telephone
to be physically factory reset?