As mentioned above, you simply cannot use the 192.168.1.0/24 subnet at all, it's reserved for the guest wifi provision (even if you're not actually using it). As you have found, the Hub's interface won't let you select it.
So any Virgin SH3 customer trying to configure a Hikvision security camera without an NVR - give up, you'll never get to reset it's default IP address of 192.168.1.64 ?
Well the newer HikVision cameras should be set to DHCP but if not, all you need to do is to plug the camera into the Hub, connect a PC to the Hub as well, give the PC a temporary static address of, say, 192.168.1.99/24, doesn't matter what you set as the gateway address, then you should be able to get to the camera's IP address of 1.64 and configure it to something on the 192.168.0.0/24 subnet. Once done set the PC back to DHCP and let it get a new IP address and browse to the camera's new address and complete the configuration.