OpenWrt SquashFS-Images have a built-in failsafe mode. OpenWrt failsafe mode bypasses all configuration located on the JFFS2 partition (that is the writable partition), in favor of a few hard coded defaults located on the SquashFS partition (that is the read-only partition), resulting in a device that boots up as 192.168.1.1/24 on the eth0 network interface with only essential services running.
Triggering via keyboard key combination in a serial console
- Unplug the router’s power cord.
- Connect the router’s WAN port directly to your PC.
- Configure your PC with a static IP address between 192.168.1.2 and 192.168.1.254. E. g. 192.168.1.2 (gateway and DNS is not required).
- Plugin the power.
- Connect via serial
- Wait until the following messages is passing: Press the [f] key and hit [enter] to enter failsafe mode
- Press “f” and the “enter” key
- You should be able to telnet (not SSH) to the router at 192.168.1.1 now (no username and password)