In my view (works best for us) turn off all BT HH5 wifi, plug the master hub direct into one of the 4 yellow (HH5 are yellow others may be different) ethernet connectors. For best connections and speed plug the TV into the Hub Ethernet ports too rather than using Wifi if possible. At least have the deco m5 hub near to tv's - not that important though for us. (We have 2 decos downstairs and 1 upstairs and it will feed the loft too if needed!)
That usually works for us. The reason we turn off the HH5 wifi is simply becuase the Decos seem to work better for us (We are in a 4 bed house and have the main Deco near the best room TV (The HH5 is there too) We one hub serving upstairs and we have one in my office (My PC is connected to the Deco direct but all the other systems 4 Tvs, phones, printer laptops etc etc are connected with wifi.
We have the 3 hub version of Deco and did consider adding further hubs but did not need it. My satnav in the car even picks up the nearest deco when parked in the drive. too.
(Where possible we are using fixed internal IP addresses using the HH5.)
Hope that helps.
Edit: We only have HD tvs not 4k.
I connect direct (via a modem) and have removed the BT Hub entirely. We now have Wi-Fi everywhere (even way down the garden0, on the same password so never fret about connection. Three M5s.
I have my PC , a TV and a streamer on direct ethernet connections, via a switch, to Disk 1
I'm being connected to BT Wifi shortly and have already have a modem (Huawei Echolife GPON terminal) fitted. What settings need to be changed for the Deco M5 system to work as you describe above? Thanks
It was very easy. I plugged a Deco into the modem, used my iPad to control it. It suggested a PPOE connection. I agreed, gave the details that I got here - firstname.lastname@example.org (?) and password BT and seconds later it was done.
I'm colour blind so I needed help in working out the colours of the one LED. I did all this a couple of months ago and have not thought about it since - everywhere I go in a large stone house and garden there is lashings of wi-fi.
I did have it running off the HH but my wi-fi printer was not reachable by all users. So removing the HH improved that. Changing over did involve deleting the original HH set up I had made by doing a factory reset, but that was a doddle too.