RBR750 in AP Mode on same network?

Help.

Its such a shame my RBR750 and it’s 3 Satellites are about to be returned.

They seem so good at wifi!  And support have spent over an hour or so going through what I have already tried. I bought them two days and I have spent over 18 hours trying various option. I have updated the Firmware. So if anyone can help or tell me I cant achieve my objective I would be very grateful.

Here is a synopsis of the problem:

I want to use the RBR750 in AP mode  so that my wifi devices can be part of my existing network: 192.168.1.0.

I have a BT OpenReach Modem. A DrayTek Vigor 2920 router plugs into the modem and powers all the wired pcs and wifi devices. I want to turn this wifi off and use the RBR750 and 3 satellites as a Mesh Wifi system.

The wifi devices must be on the same subnet as the wired devices ie 192.168.1.0

But I cannot get this to work!!!

If I plug the RBR750 into the DrayTeck (what ever rj45 socket I use) I cannot get any internet access and more importantly when set to AP mode it wont connect to the router- I get Magenta on the Orbi. Any wifi devices connected get an IP address of 169.254.118.x and or course are not part of the network. I have no idea where that address comes from, there is only one dhcp server on the network.

I have connected a NightHawk router in AP mode and this works for all wifi devices and puts then on the 192.168.1.0 network. If I connect the Orbi router to this router and setup it up it does work with the internet and wifi but gives wifi devices an IP address of 10.0.0.* which again is no good.

When I put the Orbi in AP mode it again gives wifi client address in the 169.254 range which does not work. Again the router shows the Magenta error colour.

I have run out of ideas.  I have raised a case but no ideas have jet been suggested.