I just had an strange problem with a rb411+xr5.
I have a ptp link with two of them (two rb411 and two xr5).
In one side of the link, say ip: 192.168.0.2, I lost a lot of pings from my pc to the routerboard attached to the eth1
If from the other point of the link I ping the same IP, I doesn´t loss any ping.
It´s like the link between my pc and the routerboard was wrong.
BUT, I changed my power supply from 18v to 24v and it stopped lossing packets.
Why is this? I mean, the wireless link was never lost, but cable had lost pings.
I know the cable doesn´t have problems, because I tested it and changing the power supply stoped the problem.
The other rb in the other side of the link still has the 18v power and dowsn´t have any problems.