A while back I made a post about RDP sessions dropping anytime traffic originated behind my 450g box and had to pass through our Cisco ASA 5520. Connections were always good if I did not pass through the ASA. The following rule stabilized things a great deal, but not a 100%:
ip firewall mangle/add chain=forward action=change-mss new-mss=1310 tcp-flags=syn protocol=tcp
tcp-mss=!0-1448
I have a very similar problem of broken pipes and connection resets when using ssh, but the problem only occurs if traffic originates behind my Mikrotik box and passes through the ASA.
I can connect to the same remote servers from a publicly addressed box, passing through the ASA without any dropped connections.
The problem occurs many times before I can even login and several times over a few minutes after the login.
Any ideas how to fix this so connections are stable?