If you have had a problem with your 4GR after making configuration changes, you can use the Factory Reset capability.

To perform the factory reset, press and hold the reset button on the rear of the system until the LEDs are quickly flashing red (10 seconds).  Then release.  

The system will take a while to reset (LEDs will go through the following pattern: middle green, outermost blinking, automatic reboot, middle green, left-most green blinking, searching pattern). Please do not remove power during this process.

After the factory reset process all configurations to factory default (including all passwords to those shown on the bottom label).

For security purposes, this functionality can be disabled via the Local Configuration Page (Administration > Firmware).