Reading this post makes me believe that the issue isnt actually with the port forwarding as you have tried both the hub in router mode and your own router, this would more than likely point to the host itself causing the problem. When the hub is in modem only mode all ports are forwarded except -
TCP & UDP ports 135, 137,138 – Used by the NetBIOS service NetBIOS services allow file sharing over a local network. When exposed to the Internet, it can be exploited to carry out malicious activities such as Distributed Denial of Service (DDoS) attacks or to gain unauthorised access to systems on a local network.
TCP & UDP port 445 – Used by the SMB protocol Port 445 is vulnerable to a number of attacks which target vulnerabilities in systems running file-sharing services. This port is used by various malware strains to gain entry to a network, namely the WannaCry and Nimda malware variants.
These ports are blocked by virginmedia before they even get to you.
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I wonder if you have resolve this. I am also facing same problem here. Even got new TP router while SH3 is in Modem mode. NO PORT FORWARDING WORKS!
Needless to say Virgin Media help is non existent. Called 3 times...only get answer after 50+ mins ;waiting. The person who answered only pointed to web site they have about port forwarding. Nobody could help with why ports are still blocked. External port I used was 8080 forwarded to internal IP:80