Some websites not loading on 2 routers

RouterOS General
1

Hello,

I have installed many mikrotik routers who still works for years without any problems but I have problems with 2 of them and I could not find a solution .
I have one RB951ui-2hnd and one Hap Lite and they don’t load all the web pages no matter what MTU i use, mikrotik version or dns . They are not loading/not loading web pages randomly : no matter what i change on them i can’t load speedtest.net for example .
I should mention that i not use the proxy server feature on them .

If i use them as switches or ap switches withour routing i can load this web pages .

If any of you who encountered this problem ? Is possible for this routers to have a hardware problem ?

Thank you for your time and please excuse my poor English .

Best regards,
Chris

2

Things to check:

  • Check system > Routerboard > Firmware to be up to date
  • Save the configuration by using /export to a .rsc file, then issue a reset to no defaults, then reload the file.

If this doesn’t fix the issue, netinstall them.

3

Mss shaping through mangle rules is the solution

4

Thank you for your responses !
I will try both suggestions and I will post here the results .

Have a nice day,
Chris

5

If you are connecting via PPPoE ensure your profile is set to allow MSS Clamping.

The quick way to check if this is active is to see if there are two Dynamic Forward Mangles rules. If not then it’s not running.

Here is a link to another forum post on the subject - http://forum.mikrotik.com/t/inconsistent-access-to-internet/25894/1

6

It was the MTU on the bridge !
When I added the vpn to my office (pptp with eoip) and bridged the eoip with switch master port, the bridge “Actual MTU” value changed to 1408 and the MTU field was grey . I added 1500 to the bridge MTU field and everything is working now .
Somehow, the MTU field is gray (auto ) on these 2 routers and I didn’t bothered about this setting as everything worked “on the fly” with the rest of my routers for years .
On my previous attempts to resolve the problem, I changed the MTU only on the physical interfaces but never on the bridge .

Thank you for your responses, they guided me to find the problem !
Chris

7

I’ve seen that before :slight_smile: When an EOIP tunnel is added to the bridge the bridge MTU automatically drops to equal the smallest MTU of the interface in it..

There is a setting on the bridge to “not” automatically adjust MTU but this can lead to fragmentation.

Soemtimes the best solution for an office VPN is routing (or IPSEC tunnel) rather than bridging EoIP unless you need both ends on the same IP range ?