Hi

> 3050/tcp filtered unknown

> (filtered is set for any not open port, right? nmap for windows)

"closed" is closed.
"filtered" says: the port is propably open, but not reachable for your ip.
Check for firewalls on the server. iptables, maybe.

Resume searching other problems, when this one is solved.
As long, as you don't get "open" on 3050, there is no chance to connect.

Regards,
Steffen