Reply To: Port Forwarding stopped working

Its a special feature of your router if you can connect to the WAN-address of your router. And since it is a feature of your router it might not really go that far until it is reflected back.
This is not possible with my setup, which is rather special going through two routers in series, one to separate VoIP for my house-PBX and forward everything else and one to do the real router job (I wanted to keep that router due to VPN functionality).

So the only way to check if my port forwarding works is the three digit number after UDP2-port (my port forwarding works with 321, without port forwarding it is 381).

I do not understand why changing your provider IP-address breaks the port forwarding. I’m pretty sure you only get a single IP-address from your provider. All routers I know only need an internal (LAN-)address for the port forwarding, since the router IP-address is defined by your provider. But maybe it is a misunderstanding?
What you might mean is that your computer on the LAN gets a different IP-address every time you switch it on (or after a longer switch-off-period). This can happen if you use DHCP (or automatic) for the method to get an IP-address for your computer.
Static IP would solve that, but then the static IP must be out of the range of the DHCP-distributed IP-addresses. Check the DHCP settings of your router for that. But then this network interface won’t work in a different network and may even cause network problems there.
The better way is to identify the DHCP-IP-address with the MAC-address of the network interface of your computer. Then it is still DHCP, which works in any network, but you still get the same IP-address in your own LAN. Since every router is different, you have to find yourself how to do it with your router.

Maybe that helps a bit.