Machine connection over VPN

Have managed to set up a VPN connection from my MAC using Tunnelblick to my home router running OpenVPN so I can get to files when away from home.

I can connect to my NAS box using the IP address and port in Firefox. However when I try to connect through finder > connect to server I get an error telling me the server does not exist, have tried afp and smb without any luck.

Now am new to all this, and amazed I managed the VPN, and no doubt I am missing something simple, but what??

Thanks

FTD

I've not used Tunnelblick but is it possible you are only allowing port 80 and 443 over the VPN?