either stay in.....
or try playing with the position.
from what you say ... the waves are OK through the thin inside walls ... but the outside wall is just too much.....
(rain can be enought to spoil a signal accross a garden)
think of the signal layout like a tray of water
ping the middle ... nice even ripples
ping the side opposite to the target... and by the time the signal gets there it will be weak
stick a barrier in there and you'll only get weak reflectons.
the golden rule is high and central - mine is upstairs biassed over towards the garden side (the other side is bedrooms, bogs and parking - so no serious coverage required except for phone - which is ok)
you can't definitively answer this question .... you need to tinker with the position of the base unit until you get it right.
you're looking for the path of least resistance -
walls are obvious ... but the microwave, telly, fridge or anything else with a magnetic coil is also a barier.
1" to the right could be enough