VPN traffic blocked

I need to connect two DD-WRT with configured OpenVPN.
My setup is working on TAP protocol UDP and 55555 port just fine in direct WAN-WAN connection, and in two remote locations.
When I connect it from behind a MT router, the setup connects (OpenVPN client status is Connected, Server list the client as connected) but no traffic is forwarded through the VPN both ways.
Can’t even ping server from the client side, and client from the server side of VPN tunnel.

I’ve forwarded the 55555 port on MT through Firewall-NAT
Created new NAT Rule (in general) Chain dstnat, Protocol UDP, dst port 55555 (in action) dst-nat to adresses: 192.168.0.10(WAN IP of the DD-WRT OpenVPN server) to ports 55555

Do i have to create additional Firewall Filter Rules for this to work?
How to make it work?

Block Port 1723 and 1701 tcp in chain forward in firewall in your router