Has anyone experienced something when LAN Ports on a 2680n suddenly stop passing traffic?

I have a device that does this, the wireless continues to work, but trying to connect to anything connected via ethernet I can't reach (and they can't reach anything else) - Link lights are on, and all appears 'well' but there is no traffic passing anywhere.

Ideas anyone?

try at lan>general>lan 1>details page > & set up and set the DNS manually
if will help and also maybe tick the option Force router to use "DNS server IP address" settings specified in lan 1