I have a RB411AH 200 feet in the air. I lost Ethernet connectivity with it from the bottom.
Changed everything at the bottom including the POE-24i and still got the same symptom.

Sent a climber up to take a look.
Board lights were on. Had him disconnect the Ethernet cable and we tested the line. It passed.
Had him pull the board and bring it down.

On the bench I noticed when connecting power to it the lights would come on but it would not boot.
I removed the XR5 card and tried again. This time it booted!
Ok, bad card. Grabbed a new XR5 card put it in and tried again. No boot!?
Removed the XR5 and then it would boot.
Obviously an issue with the RB.

After all of the capacitor issues we have had with these devices (RB450's, RB750's) I went ahead and swapped about C818 & C819 from 6.3v 560uF (Solid blue, Gold strip, T on top) to 6.3v 1000uF Aluminum solid capacitor. This fixed the issue.

I was just so used to how well the RB500's held up (except the ether1 chip issue) that I expected the same thing from these.

-Louis