My Homehub 6 is located close to a brick wall in a bedroom. A Panasonic smart TV located almost directly beneath it in the lounge suffers from frequent buffering. A Samsung smart TV in another bedroom very seldom has any buffering. Both TVs are about the same distance from the Homehub, the Panasonic being a vertical distance and the Samsung a horizontal distance. Does the Homehub have little vertical coverage or does the Panasonic have poor wifi processing? Any suggestions?
My Hub 6 is located upstairs in a 2 storey house the Panasonic tv downstairs is connected to the 5 ghz band and streams perfectly in uhd with no buffering. The other tv and various devices around the house all also perform perfectly and the wi fi extender in the summerhouse about 200 metres away also connects at full strength to the hub 6 via the 2.4 ghz band the tv and other devices connected to the extender also work without buffering. however the internal construction of the walls of the property will affect the performance of the wi fi signal.
The radiated wifi signal from the hub won't be uniform in all planes, try different orientations of the hub, even laying it flat to improve the signal to the downstairs TV
All my other devices connect perfectly well so I think that Licquorice has probably got it right in his reply.
Remember radio signals are a dark art. I would not personally advise you to change the orientation of the Hub, It is designed to be seated in a vertical position. Rather obtain a wi fi extender and see if that improves the situation with the Panasonic TV. I use Netgear Extenders but there are others to choose from, I seem to recall that the Hub 6 had 7 differently orientated antennas built in so keep it in the vertical Position.