Sky wifi max hub no connection

[Loz5]

I've had the sky max wifi hub for about a month now. The speed to the hub is genuinely quite good but devices don't seem to receiving this speed. For example my husband can't play COD online due to the really lag he gets. Speed the hub ranges at 40mbs. 

It also struggles to connect to my main sky box..it seems to work better from a generic wifi extender..sky have said they've sent a booster out to me but what will this do? It's not going to fix the lag problem