I have a router running dd-wrt. sometimes the dd-wrt web ui crashes and you cant access the interface, but your WAN connection works, and you can still login via ssh

On the dd-wrt command-line there are a couple of utilities available to let you start and stop services. If your httpd is not responsive, just login to the command-line via ssh and run the following commands:

stopservice httpd
startservice httpd

Apache will then restart and you’ll be able to login using your browser again!