I'd suggest doing more experimentation with the location of your hub, do you know where your mast is?
You shouldn't see that huge of a drop from outside to inside, keep the hub at least a foot away from window frames as they can mess with the signal, and once you know your mast location you'll want to play with the location. I get the fastest speeds right next to an exterior wall, not next to the big bifold doors - presumably they affect the signal.
Even a 30cm difference in location can make a big difference.