I have a rash of RB411/411r's failing in the field after exactly 4 years of service. I suspect some sort of software timer. After two that had been installed on the same day in 2008 failed, I looked at my records and checked out the next RB411/RB411r in the sequence and updated the firmware from 3.27 to 4.x, upgraded the license also. Unit's power up, but the ethernet is not functional, and connecting to the serial port, no boot sequence is seen.

This shouldn't be happening. Help!

To clarify, the third in the series failed also, after being upgraded from v.3.27->4.11 and of course, the license upgraded also. What I didn't do is upgrade firmware.

What I'm doing to fix, in absence of any information at this point, is to upgrade the RB11/R's in the field that were installed in sequence after the 09/2008 date is to upgrade them to v5.20 and upgrade their firmware to 2.41.

This is too much of a coincidence (no extreme heat event or widespread power outages)...I suspect a timer/bug in the firmware (v2.15).

The devices completely shut down, won't boot, won't reset, no activity shown on the serial port, and no ethernet. Light's on board show they are powered up.

I guess it is rather hardware timer, end of life of some components. Look for bad caps (bulged green capacitors) on the board. RB411/411R also affected by Suscon SJ series.