No responses when ping to dhcp server and winbox can’t login by ip(LAN OR WAN) only by MAC,device under dhcp server can’t connection to wan
I have setup a pppoe client before but it disappeared,but if I ping to google dns(8.8.8.
by routeros’s ping tool ,I can still receive the responses from google dns
all thing back to normal after reboot,the secend time it’s happen
Well, just read my earlier post:
http://forum.mikrotik.com/t/aperiodic-down-lan-no-internet-access-on-rb-750/64353/1
or http://forum.dug.net.pl/viewtopic.php?id=22261
Is there the same problem? I can’t resolve this trouble!!! I have logs from Wireshark (tons of logs, about 3 Gb)
It’s my ‘nightmare’, just horror: i must every time (when it need) reboot/restart -power off, power on. All back to normal after reboot.
Have You any solution?
Defective boards. Our Rb750 were unstable also, had to replace them with RB751. I know it’s different product but atleast it gets a job done.
to: bysard
Are You sure that was defective board of rb 750?
In my case it was the RB750. It also sometimes lost bridge configuration (bridge was there, but no dedicated interface). After reboot all was fine.
you have not used ‘embedded’ option switch? In this case ports eth2 to eth5 are bridged. There are LAN ports and eth1 port is WAN port. I think you know it - you can read manual! 
I’m very interested WHY you make additional bridge configuration? What for?
I NEVER use default configuration. And ports are not bridged by default when you don’t use default config you know… Why i’m making additional bridges? Because I need them? And also in the past you couldn’t log src-mac addresses from interfaces alone, you had to use bridges for that. And this thing happened in the past.
Well, i use MikroTik software since 2005 year, hardware - little be later. Ok, i know about this. I come from Poland and my English is not quit correct /that’s my opinion / I try to find the same symptoms in yours and my case. Have you read my earlier post on this forum? Is there the same problem with RB750?
update firmware to 3.07 yesterday,hope it wil be fix
I have read your post. I haven’t experienced your simptoms. In my case it couldnt be configuration because I used a new RB750 with only basic IP and default gateway set + OSPF. I’ve also experienced when I transfered something from one port on MT to another the router’s CPU went to 100%, pings rise up to 50ms. I stopped using RB750, seems to be the most effective technical solution in this case. There were just too many problems with that model in my experience.
Sadly to say, RB2011L seems to be going the same path. 
to: yukiaoi
I’m very interested in your… DOWNGRADE to 3.07. How about properly working? Could you write a little more? Please!
to: bysard
Thank You very much for your help. I’m very glad to hear a bit of your opinion about RB750 and BR2011L - mine is the same.
There is only one thing to do: going to change hardware.
He didn’t mean downgrade of RoS, but upgrade of firmware.
/system routerboard print
/system routerboard upgrade
Well i made upgade, and now i have:
[admin@MikroTik] > /system routerboard print
routerboard: yes
model: 750
serial-number: 3B02026F#####
current-firmware: 3.07
upgrade-firmware: 3.07
[admin@MikroTik] >
thanks once more again bysard
Maybe this will help.
2013.05.12:
It did not help.
I had to restart the Mikrotik RB750 several times (3 times)…
I’m going to change definitely hardware.