Can't access microsoft sites or services after bridging lan with eoip

RouterOS Beginner Basics
1

Hello everyone,

we are trying to connect our 2 remote sites over eoip tunnel.
Both sides are using NAT so we have one virtual mikrotik which connects them.

The sites see each other, pings are working, dhcp would offer ip address to remote site if not disabled, but when the bridge with lan interface and eoip tunnel in it is created,
Skype for business stops working (we can’t even log in), also we can’t reach technet.microsoft.com and some other Microsoft sites.
It’s the same for our, or google DNS. The default gateway is our WAN interface, disabling all reject and drop rules in firewall doesn’t help either.

The version of RouterOS is 6.34.3 on every device.

The shared network is 10.100.0.0/17
Site 1 gateway is 10.100.0.254
Site 2 gateway is 10.100.1.254
Virtual mikrotik has 10.100.127.254

When there is only lan interface in the bridge, skype works normally. After enabling the tunnel, the above symptoms happen.

I would be glad for any help or opinion on this.

Thank you in advance.

2

Hi,
print out your NAT rules please ( on both sites)

3

From our provider we have internal addresses, which are
10.0.X.254/24 as WAN gateway on site 1, the public address serves whole building, not only us
192.168.Y.254/24 as WAN gateway on site 2, router is behind modem which have public address
Both sides have srcnat masquerade out WAN

Virtual mikrotik has public address

Tunnels are configured public to public

I should also add, there is 3rd site, without NAT, WAN is public address, same problems.

4

i suggest you to printout you entire firewall settings

5

Most probably it is MTU problem.

6

@jarda : i think it’s MTU too but each site has its own internet(provider,gateway,NAT)
how it’s possible some site would be unreachable just when bridging eoip with LAN ??

it seems sites reaching internet over EOIP due to the wrong configuration on default gateway or NAT , what do you think ?

7

http://forum.mikrotik.com/t/some-websites-not-loading-on-2-routers/95502/7 check this thread. It could easily happen that bigger packets do not pass while not so big packets do. Then some sites are accessible and some not.

8

Thank you both very much for your help. MTU was the problem. Now it’s working correctly.

Have a nice day

9

Hi,

Can you post how you resolved the problem?

What was the old MTU set at and to what value did you change it?

Just for future reference if someone in the future is having the same issue as you.

10

When you add Eoip to bridge, the bridge MTU will change to a lower value . You need to modify the bridge MTU back to 1500 .