CISCO 2800 Router : How to reset to default settings

In August 2025 I got hold of two second hand CISCO gadgets a switch -3570 series and a 2800 series router from a local supplier for my homelab. Unfortunately, the 2800 series router had the previous configurations in play hence needed a password to access the configuration mode. This calls for a reset to default settings.

In this article, I will take you through the process of resetting the 2800 series router. To achieve the aforementioned, We will need to boot the router into ROMMON mode then change the configuration register to 0×2142 from the default of 0×2102.

ROMMON mode

For the router to be reset, there is need to navigate the router to ROMMON mode before it fully boots into the running mode. For the 3560 router there are 2 ways to get into ROMMON mode. The first option is to use the break command. The second option is to unplug the flash card.

Using the break command

To use the break command to go into ROMMON mode, We need to power off the router, connect our computer to the console port then connect to Putty. Power on the router, at the first sign of life on the console go to special commands on putty and click break. This will make the router boot into ROMMON mode.

Unplug the flash card

To do this, we will power off the router then unplug the flash card as indicated below.

When we power on the router and it will boot into ROMMON mode as below. You can then plug the flash card.

In ROMMON mode, we need to change the configuration register to 0×2142. We use the “confreg 0×2142“ command. The router will prompt for reset, use the “reset“ command.

After reset command, the router will restart with a fresh running-config. We then have to Copy the running configurations to to the start-up configuration as the below command.

We now have to revert the configuration register to the default value of “0×2102”. We need to navigate into the global configuration mode with the “configure terminal” command. While in this mode, we use the “config-register 0×2102” command to change the register as below.

Finally we can restart the router with the reload command. We now have a router without the secret/password to navigate into configuration mode.