Why does the subnet ping but resources are not available?

Question

VPN

Two remote devices mikrotik (accepts the connection) and kerio control (initiates) are connected by an ipsec site-to-site tunnel.
There is a tunnel, routes to both networks were automatically created by politicians. There are pings, but there is no access to resources. For example, I'm trying to rdp from LAN for Mikrotik to a machine for kerio control - it prompts for a login password, but the session does not open. It is the same with access to files via SMB and any other classic operations within the network.
When connecting to Kerio through a proprietary VPN client, everything is fine. Through Mikrotik - no access.
ps : I noticed a difference in ttl when pinging through a corporate client (pinging kerio - ttl=64) and when pinging from LAN behind Mikrotik (pinging kerio - ttl=63)
Help)

Answer 1

Maybe the firewall closed access and only ICMP is open?

Answer 2

On both Mikrotiks, run:
/ip firewall mangle
add chain=forward action=change-mss new-mss=1250 passthrough=yes tcp-flags=syn protocol=tcp out-interface=all-ppp
add chain=forward action=change-mss new-
mss =1250 passthrough=yes tcp-flags=syn protocol=tcp in-interface=all-ppp in new-mss=...