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unable to port forward - is this a CGNAT issue?

Level 2



I have recently switched from ADSL to NBN. Since I switched I cannot get port forwarding to work. 


I have tried all the solutions that I can find on the community forums but non of them worked. I spoke to TPG online help but they were not able to fix the issue.


I have not changed any settings in windows since the switch to NBN, I have double checked my windows network settings, I have checked that my firewall is set up correctly to allow the port through, and I have re-installed the game.


My external IP address is different to my default gateway. When I do a tracert, the first hop is to my modem and the next hop is to another private IP address


Is this issue caused by CGNAT?


I would appreciate any help you can provide








Is your game accessible from another device on your local network?

Does your game server have a fixed ip address in your wifi router?

ADSL had a static ip address. With NBN, you have a dynamic internet ip address which can change from time to time.  You can subscribe to a Dynamic DNS service; the router will have some setup to handle the change of external ip address.

Level 2

Hi David


There are no other devices on my network, only one PC connected by cable


My internal IP address always remains the same when I reboot the router, but the external IP and the default gateway both change.

    - internal IP is always

    - externa IP is the format

    - all parts of the external IP have changed


When I try setting up a static IP address in windows I get a warning that the default gateway is not on the same network segment (subnet) that is defined by the IP and subnet mask. 


is this informtion useful?


Thanks Smiley Happy



Routers are normally You should set up an address reservation in the router for the mac address of your computer. Make it

Change windows so it accepts dhcp settings from the router (ip address, default gateway, subnet mask). Alter the port forwarding to match.

The 10.20 address is part of TPGs network.  "10.' addresses do not appear on the internet.

Somewhere in the router will be your real external ip address given by TPG.  The DDNS function in the router will keep your game server accessible to internet users, without them having to know your external ip address.

Level 2

Definitely CGNAT issue. Might have to pay for dedicated IP service or try other remote control software.