Port forwarding

[#1]

I have followed instructions on a number of websites to allow port forwarding on my Plusnet Tg582n router e.g. http://support.zen.co.uk/kb/Knowledgebase/Broadband-Technicolor-TG-582-Configure-Port-Forwarding.
However, I am still unable to connect to the router e.g. using this website http://www.yougetsignal.com/tools/open-ports/; all the ports including the one I have just set up, as well as preconfigured ports e.g. 22/80 etc. are apparently closed. I have also tried to ping the router ip address from a linux server which is external to my home network.
How can I allow an external connection into the router? I am assuming this is an issue with the firewall, but according to the 'Technicolor gateway' configuring the port as described in the listed article should allow an exception in the firewall. I'm rather confused now!

[#2]

Plusnet provide a firewall at their end of your broadband connection.  You can see the available settings here:
https://portal.plus.net/my.html?action=firewall
To turn it off, you need to select the 'Off' option and then force your connection to drop and re-connect for the change to be made effective.
HTH

[#3]

Unfortunately, when I checked, the Firewall was already set to off so that doesn't seem to be the problem in this case. Are there any other settings I need to change? Also I noticed that every time the router restarts, the external ip address changes. Is that correct?

[#4]

that will happen unless you have static ip - which is available for a £5 one off charge on some accounts.

[#5]

Ok, that's useful to know, but presumably, providing I know the external ip address at a given time, I should be able to use the port forwarding service. I am still confused as to why connections are blocked as the plusnet firewall doesn't seem to be the issue, and I have set up the port forwarding options on the router to allow external traffic on certain ports?

[#6]

Are you trying to enable remote access to the router itself?

[#7]

Yes. I would like to make a VNC connection from outside the network, to a computer within the network. I have followed the instructions on the following website http://support.zen.co.uk/kb/Knowledgebase/Broadband-Technicolor-TG-582-Configure-Port-Forwarding to open one of the ports, but using this website http://www.yougetsignal.com/tools/open-ports/, the port I have setup is apparently still closed. The VNC link works within the local network, but if the port isn't open to incoming connections, I won't be able to make the VNC connection once I am outside the network which is what I am trying to do.

[#8]

So no, you're not trying to enable remote access to the router's web interface.
Apart from checking that the VNC server is configured to allow external access, I've heard that port forwarding may work better if the target device has an IP address assigned by the router DHCP rather than setting a static IP address on the device itself.

[#9]

Also remember that the port will not appear open if there is no listening service running on the target machine.  It is not sufficient to just enable pass through (forwarding) on the router, there has to be an active listener running.
Further is there a software firewall (windows or some other) on the target machine?  The port in question needs to be open on the target machine.

[#10]

Thanks for your help. It was the software firewall on windows that was causing the problem.