Hello
rb411AH and os 5.25 and link ptp AP mode: bridge,and station mod: station bridge, ip set in bridge
wlan up too 40m
and Everything is ok
BUT
Log:
May/23/2013 19:17:46 interface,info ether1 link up (speed 100M, full duplex)
May/23/2013 19:17:47 interface,info ether1 link down
May/23/2013 19:17:53 interface,info ether1 link up (speed 100M, full duplex)
May/23/2013 19:17:54 interface,info ether1 link down
May/23/2013 19:17:57 interface,info ether1 link up (speed 100M, full duplex)
May/23/2013 19:17:58 interface,info ether1 link down
May/23/2013 19:17:59 interface,info ether1 link up (speed 100M, full duplex)
May/23/2013 19:18:00 interface,info ether1 link down
May/23/2013 19:18:03 interface,info ether1 link up (speed 100M, full duplex)
May/23/2013 19:18:04 interface,info ether1 link down
May/23/2013 19:18:05 interface,info ether1 link up (speed 100M, full duplex)
May/23/2013 19:18:06 interface,info ether1 link down
May/23/2013 19:18:08 interface,info ether1 link up (speed 100M, full duplex)
wire :tiko net out dor CAT5 , 60meter
Noise sources did not pass through the wire.
The use of Ethernet on average: 6m
This problem. During the day there is only a few minutes.
ether1 conect to cisco 2960
routerboard voltag 22.4v
I do not know where is the problem
Try change POE injector. If you use this http://routerboard.com/RBPOE
The biggest source of the problem …
I,m use VOPTEH poe model
24v 2a
ok
I’ll try tomorrow.
IF you use NSTREAM mode, could you try with the NV2 mode and report back please for start? 
What have wireless protokol common with ethernet flapping?
When I had in bridged mode wan1 and eth1 on my RB411 and I had Nstream, I was in the same situation as capitan.
When I afterwards picked the NV2 protocol, everything was working grate.
After that, i only use NV2 nomatter what. 
I don’t know what is common with these things, I’m just writing you down what I have encoded with my RB411AH routerboard. Maybe a coincidence?.
Another ethernet flapping on the SAME model boards, I encoded it with the PSUs of them.
When I change the PSUs, everything was OK.
EDIT: You could encode the same problem, if you are on a mountain with HIGH RF levels from FM and TV stations.
There is no definitive cause for that ethernet port flapping:
http://forum.mikrotik.com/t/new-ethernet-port-flap-issue-enquiery-pls-join/49200/1
and the MT is not seeing anything broken with it…
our solution is using the SFTP (not FTP) cable with the SFTP connector…
and if budget ok, use the ubnt 24 watt poe instead of using mikrotik power adapter + poe.
then you can enjoy your time.