New Transmission add-on thread

I'm having the same problem as the guy a bit further up.

Transmission says that "Port is closed" when I check the port in the UI menu.
I've tried a variety of versions, neither of them are working.

I've checked my router, and the port is open. (Even tried to change the port, and I can see that my router automatically changes so that the chosen port is open)

I also tried to use the "in-built" torrent client, but this is not working either.

I recently moved, and as far as I can remember, I was able to use the Transmission Add-On before this.
I've brought the router from my old house, but I've changed the ISP.

I first thought that the ISP in some way was blocking Torrent traffic, until i booted up my Ubuntu machine and tested Transmission from this. Works like a charm.

I'm lost here. Are there any others who have encountered this (and found a solution)?

EDIT:
Oh, and...

Current version:
RAIDiator 4.1.7
Transmission 2.31