IPSEC Client behind Mikrotik NAT

Hi!

I am using IPSEC client (in this case Checkpoint) to connect to a Checkpoing Firewall.
I am behind a Mikrotik device that makes masquerade or src-nat action against Internet.

Problem I have, is IPSEC sessions is established but I can never get any traffic through
IPSEC tunnel. BUT it works on one Mikrotik device at another place, but not here.
I have tried to compare the configurations but cannot see any difference that would
affect this.

Anyone has any ideas what can be the cause?

With such parameters - no ideas.