My 2820n has been powered on since July 2011.

Yesterday, probably for the first time, one of its 4 ethernet ports stopped working.

(The symptom was that my desktop, which was plugged into port 1, lost network connectivity. Moving the desktop's ethernet cable to a spare port on the 2820n restored connectivity to the desktop, moving it back lost connectivity.)

I powered-off the 2820n for a minute or two and then turned it on again, whereupon port 1 resumed working.

I saw no syslog management messages relevant to this event.

Could this be caused by a vigor OS fault?