Here is a list of things that can help for poeple using firewalls, anti-virus and routers.

1. If you are unable to connect to a server and you verified the server address, port and you are sure the server is online.
2. Close all your firewalls and try to connect again. If you succesfully connect to the server with your firewall offline it means that the port or/and ip of the server is getting blocked by the firewall you are using.
3. In almost all firewall programms you can set it to always allow a specific port,ip or programm to be accepted instead of blocked.
4. Close your firewall when using your ventrilo(not recommended)
5. If you were able to connect to your server and one day you try to connect and you are unable to connect
6. make sure that the server is online
7. Close all your firewalls and try to connect again. If you succesfully connect to the server with your firewall offline it means that the port or/and ip of the server is getting blocked by the firewall you are using.
8. In almost all firewall programms you can set it to always allow a specific port,ip or programm to be accepted instead of blocked.
9. Close your firewall when using your ventrilo(not recommended)
10. In some rare cases, routers can block the ports rendering the connection to servers impossible.
11. You will need to open/foward your server port. Refer to your router manual to learn how to foward ports.