Not quite sure what happend the first time but the first reply disappeared into oblivion. So, I'll try again...
The SH2 needs to be directly connected to the phone socket for digital voice. I did mine this way:
Smart Hub 2 (SH2) router settings:
DHCP off. (The addresses here are best set as static addresses).
Router itself set to a static IP of 192.168.1.254, (the default).
Subnet mask of 255.255.255.0 or /24, (also the default).
DMZ host set to 192.168.1.2 (This helps with double NAT problems or at least it takes care of the port forwarding on the SH2. There is still address translation happening, however, so you may still have problems with multiplayer games, UPnP etc. In fact, you only really need this if you have incoming external connections to a server etc. Personally, I’ve never found double NAT to be an issue and I don’t use the DMZ setting. Note, this setting allows a lot of traffic to effectively bypass the SH2 firewall, so you are relying on your own router’s firewall for security, just as if it was directly connected to the internet).
Turn off both Wi-Fi bands in favour of your own router. (This may also be a good security move if you do enable the DMZ host. I would still expect Wi-Fi traffic on the SH2 to go through its firewall but I can’t be sure how they’ve set it up internally).
Connect the DSL port to the phone socket on the wall, (or the WAN port to the ONT, if on FTTP).
DV phone/extension then plugs into the phone socket on the Smart Hub 2.
Own router settings:
DHCP on, range 192.168.0.2-192.168.0.200 (Note the 0 in the third position, making this a separate network to the SH2. This is deliberate, not a typo).
Router itself is on a static IP of 192.168.0.1
Subnet mask of 255.255.255.0 or /24
Enable the EWAN port and set it to a fixed IP of 192.168.1.2, (so it is part of the SH2 network).
Gateway set to 192.168.1.254, (again, pointing to the SH2).
DNS set to 192.168.1.254 (or whatever you usually use).
The EWAN socket on your own router (probably 4) connects to a LAN port on the SH2. (NB. This will not work if you use the DSL port on your own router).
