I recently ran into a problem where I was not able to ping, SSH, or otherwise connect to a computer on my home network. My router is using DD-WRT. Both machines were wired in.

This seems to be a common issue

In the DD-WRT admin page navigate to Administration -> Commands.

Enter these commands (both lines at once) and click Run Commands. 

swconfig dev eth1 set enable_vlan 1
swconfig dev eth1 set apply

This should fix the problem immediately.

Occasionally, I encounter an error when running these commands. I do not understand why.

To troubleshoot this. I will do the following (not necessarily in this order, and often, multiple times).

  • Run the commands one at a time.
  • Switch eth1 for eth0.
  • Wait a while.
  • Run both commands at the same time again.

Eventually, the commands run successfully.