Possible blocked ports fault

[#1]

Hi all,
I used to flawlessly run several servers/services on my Plusnet connection a few months ago, then one day, I suddenly started getting issues - game servers not showing up in lists anymore, people not being able to connect to my Teamspeak server some of the time, my remote connections not working, etc.
I've got some ports forwarded on my router and I was using those connections about an hour ago. Then I added another port and another service but couldn't get it to work - so I did the obvious thing of switch the router off and on again.
Unfortunately, all this seems to have done is stopped all of my port forwarding rules from working at all.
I phoned Plusnet and they said to post on the forums so this is me posting on the forums.
Any ideas on why my open ports are seemingly being blocked by Plusnet or some link somewhere between my router and the internet? All is well internally with my connections.

[#2]

Sounds like a router configuration issue. What router are you using?

[#3]

This may seem like a simple question, but are you connecting to the correct IP when connecting externally? I ask as your account has a dynamic IP address so changes on each connection.

[#4]

Lol, yeah dynamic IP might not help. Another thing to consider is whether the router supports loopback. I assume when you originally set up forwarding you tested it the same way but the router I use with PN didn't support loopback for the first day or so. I've no idea why I just remember writing a ticket and doing a quick test before posting only to discover that it was mysteriously working. At least that was one less ticket in the queue