The Asus is part of a wireless mesh system so I guess as a router is the best.
I'll probably have to disable the wireless feature in the SH2.
The Asus needs to be set up with a different IP subnet to the hub.
Set the Asus WAN as type static IP address and give it an address of 192.168.1.10 and Gateway 192.168.1.254
Set the Asus to use 192.168.2.xxx as its DHCP subnet.
Connect a hub LAN port to the Asus WAN port.
You will then have 2 subnets, you can either use both or turn off the wifi on the hub and just use one subnet.
Thanks for your help I've got it working.
I couldn't find 'Set the Asus to use 192.168.2.xxx as its DHCP subnet' option though but it's working fine.
There wouldn't be an option for it, as such. It is something you would have to configure manually.