Hello, I have been trying to set up a link between two mikrotiks with EOIP tunnel. I use a PPTP tunnel between them and then make an EoIP tunnel. It’s like this :
Ether port → EoIP → PPtP connection → 3G connection - internet ← PPtP ← EoIP ← Ether port
The main reason to use EoIP is that it’s essential for me to have the same network on both sides and not be associated with any IP addresses in these networks so I have to use EoIP.
Well, the tunnel is established and the client side gets DHCP lease from server side and is able to connect to internet via server side, but it is very slow. I found out that any packet, bigger than 1400 gets stuck. For the past week I was trying to find a solution with this problem but I can’t figure out where to change the MTU and to what.
Now parameters are :
EoIP - 1500 MTU
PPTP - 1460 MTU
PPTP 3G - 1500 MTU
It seems that PPTP 3G mtu changes back to 1500 automatically.
I have also tried to set IP firewall mangle rule on 3G conn to change MSS to 1400, but apparently without success.
What should I do? please help me. 
