This would have been possible in the past with a home hub 5(a), since a firmware update went out and made them reboot with no DSL signal repeatedly they are no longer any good for that. It's still possible by replacing the firmware on them yourself but thats quite a technical task. With the Home hub 6 i would assume no, again unless your able to figure out how to replace the firmware.
These BT routers should have a modem only mode, for people that want to use a decet router, Thankfully i got my service back when BT supplied seperate modems rather than poor router/modems. It would make sence to have an access point only mode too, so they aren't just being thrown away as usless just filling up a land fill when people upgrade, or just stop using them because they are poor routers.
Try it and compare results. You will only be able to use the Openreach modem in conjunction with the HH5 though, as the HH6 doesn't have a WAN port (except the FTTP version).
Great. And connecting the TV to the HH will still work if the HH is just acting as an AP?
In my experience, no.
I'm also using the HH6 as my main router and an old HH5 as a wireless access point, when I tried connecting my youview box to the HH5 with an ethernet cable it would work for so long then IPC6023 error crops up repeatedly.
I got round it by connecting an unmanaged switch to the HH6 and connecting the youview box and HH5 to that.
Don't forget to disable the DHCP server on the HH5 or you could get IP address clashes
It can work, but in my experience, you can get a 2 devices on your network trying to act as an igmp proxy and looping the multicast pakets all over possibly saturating ethernet links.
I had to remove a HH4 acting as an access point from my network for this reason, it would intermittantly completly screw up IGMP multicast, saturating network links and causing constant IPC6023 glitches and huge internet slowdown .
The Home hub 5a running open WRT on the other hand, flawless, IGMP proxy disabled and setup as an access point only and the wan port addedd to the network switch, but getting open WRT on there it's not easy to do!