Do certain ports get blocked?

[#1]

I have a static IP address set up for my account as I am hosting a web server from within my network. I currently have this working perfectly well on port 80 with my router handling the port forwarding of TPC on port 80 to the appropriate IP on my LAN. However I need to change this port to a different one (4040 say) as I need to use port 80 for something else (Guild Wars 2  ) but I do not seem to be able to get this to work, I just do not seem to get any traffic when trying to connect on xxx.xxx.xxx.xxx:4040. Do PlusNet restrict this at all? If so is there a port range I can use?

[#2]

It depends on your PlusNet Firewall settings https://portal.plus.net/my.html?action=firewall ( login required )

[#3]

And whether you've forwarded the port through your router.

[#4]

Thanks chaps, but having checked my PlusNet firewall is currently off (I didn't even know I had one  :D) and the ports are being correctly forwarded in the router - as I mentioned it's been running fine on port 80 for ages. Any other ideas?

[#5]

Have you checked that the port can be seen as open on http://www.canyouseeme.org/ or similar?

[#6]

I will check when I get in tonight and report back, thanks for the suggestion.

[#7]

and ( i know it might be an obvious question, but ) is your Web server correctly configured to listen on the new port

[#8]

Worth asking but yes I can hit it from a PC on my LAN using the new port.

[#9]

Can you connect to it when using your external address from within your LAN,  this will test if the router is configured correctly.

[#10]

I wouldn't expect that to work even if the router is configured correctly.

[#11]

It works fine,  by using the external address the localhost sends it's packets to the router's external (WAN) interface, and the same port forwarding rules are then applied. 
It's the easiest way to test the rules worked without access to a different internet connection.

[#12]

Have you confirmed that this works on the router Palmski is using?
I know for an absolute fact that this doesn't work on my Netgear DG834 as I found out when I tried to make my RouterStats page visible externally. I could access it via 192.168.0.*, I could access it from the office using my assigned IP, but I couldn't access it using the same IP from within my network.

[#13]

It works fine on my current Netgear N150  (been testing this over the past couple of days with http and ssh servers on my Raspberry PI),  and every other router I've tried it on over the last 10+ years!
It's possible that some routers may restrict this behaviour,  hopefully Palmski has one that behaves itself.

[#14]

The best thing would be for him to check if the loopback test works on port 80 first.

[#15]

if it helps, here's a list ( albeit slightly out of date ) of routers that support NAT loopback  http://opensimulator.org/wiki/NAT_Loopback_Routers