Hey mate I saw your post I've actually found the port forwarding rather easy on the optus seagomcom router go to nat in advanced options and advanced setup .
You should have the list of ports go add I would make sure you know what your particular devices internal ip address is and also select custom service also make sure you know the exact port that your device uses .
Usually you can input the port number into all specified fields.
Now to access from outside your home use your houses external ip with the port number e.g. 67.200.300.100:8080 (ps nor actual ip) into your web browser address bar hope this helps
That's great and all, but can you confirm the model number is the same? If it is (which I suspect it is, but seriously, be specific) then you should also note other people have been able to get it set up, but it's not always reliable.
Additionally, accessing the redirection from inside your network doesn't work (it only works if you're coming in from outside your home network).
Make a manual port forward entry pointed towards the device's IP and port then apply that and then go onto the DMZ setting for it and turn it on for the same device .. this completely fixed the exact same problem I had ..(Be Mindful that Optus has done something weird and you won't be able to view or connect to the servers external IP from within your own network ... I have literally no idea why it does this but it does )