your Register address and sip proxy seem different, do you get both addresses from iinet?

there seems no option to disable NAT with PPPoE connection, other connection type like dynamic /static ip do have that.

none of your devices working wireless still??? try log into 192.168.1.1 page, and go to interface setup, wireless, set channel as 11, disable WPS, change the SSID to a new one, check the security...

surely the utility is not compatible with win 8 yet.

try this, go to Network-> 3G and select Connect Manually of Connection Mode option.

what about your other computers or devices, the same problem??? try fix channel as 1/6/11