VO is not accessable via Internet!

VO is not accessable via Internet!

Hi,
it's not possible for me to access VO from other locations via Internet.
I've got a DSL router and maped the port 1542 which I chossed during installation directly to my client im private network. I can access my client via Internet over RTP and Port 1542 is excepted on OS firewall. Router Firewall ist off!
What could be wrong?
Tanx in advance!
B. Sadiq