@sockethead74 

The main loss of WiFi signal is absorbion by the house itself, this is none more prevelent on the outside walls sadly

For the record this is measured in -db loss, and -3db is HALF the original signal.   So -6db is HALF of a HALF, hopefully that makes sense so far!

Below are the rough guides for the effect some walls have on signal (approximately)

Stud Wall  -  3db

Wooden Door / Wall  -  5db

Brick Wall (Single)  -  8db

Brick Wall Double  -  16db

So basically, while im not sure what your house is made of... let take single brick as an example.   Note.. this is more for illustration and not how you would measure this in reality..

Start with 300mbps speed, half it 3 times (so 12% roughly) which is around 40mbps at the other side.  Add in some interference from phones, airspace, distance etc and 25/30 is expected.

In short external walls KILL signals due to their insulation and thickness, placing this beside a windows may help a bit as glass does reflect signal; but to a lower level vs solid walls.  This is why a lot of people would look to place an outdoor Access Point into their garden via a cable through the wall.