you play and test and read help on here - choose which band is best for your device/s if you are near the router the 5 band should give the best speed as you move away that will drop and the 2.4 might be better
you have 100 to the hub/modem thats as far as it goes - you cannot expect that to be the same on wifi at distance from the hub - you pay for 100 and get 100 - no isp translates that to be a guaranteed wifi speed
There is a guide on the homepage to help with what you are trying to do.
Are you really going to come back and ask another question every time you are spoon-fed an answer because this thread will end up very long and I still do not think you will ever be happy (you were asked to test wired first which is the correct thing to do).
no isp can guarantee a wifi connection. It can be affected by 1000's of things outside the ISP or your control. VM will only sup[port a wired speed. IF you are getting it then the connection is as expected.
you can get your own (better) router with better wifi and use the hub in modem mode
As a Very Insightful Person, I'm here to share my knowledge. I don't work for Virgin Media.