Agree with Ian, splitting the bands does help, I had to do it on a few BT home hubs other routers.
I had to do it on a a BT home hub for someone as their Iphone and Wi-fi calling would not work.
5Ghz is not all it is cracked up to be to be honest, i do not understand how 2.4ghz is not fast enough, until recently I only had 2,4Ghz and I was streaming Netflix anf Now Tv with no problems.
I wish we could get hyperoptic or at least Virgin, could get rid of BT hybrid system.
Desktop machine now powered by windows 10 pro, reluctantly, laptop by Linux