TX power is always a tricky thing as you want to allow for a slight overlap otherwise you have dead spots but not so much that devices connect to the wrong AP as in your case. If this is a simple work from home I would unplug the loft AP and the adjust the TX on the ground unit until the loft devices can only just see it, then do the opposite. If it's a larger office then you will need a site survey.
... View more
