[JohnWill]

Disable the Windows firewall and see if that fixes it.

[Couriant]

windows firewall from what i know does not have the option to do a range of ports.

If it worked when you tested in your network, I doubt that it would be the firewall settings.

One test you can do is put your server in DMZ temporarily and see if you can connect. DMZ should not have any rules to follow.

[Couriant]

In case I'm wrong about doubting the firewall:

http://support.microsoft.com/kb/875357/en-us

look at that and see if it helps. I would suggest looking at the advanced troubleshooting section of the link.

[meirionwyllt]

I've given up on Windows Firewall now, and it works fine.

I know I should've done this ages ago, but I wanted to keep a software firewall just in case. I even tried a FOR command to open port 5800-6000 using NETSH FIREWALL command, which put entries in the Windows Firewall Exceptions list to open each port individually. But this still didn't work.

But now, sod it, the hardware firewall of my router will have to suffice. I have switched off Windows Firewall and all is well.