raytaylor:

 

What happens if you take the antenna off and just use the internal antenna of the modem?

 

You can position the modem in the window and run ethernet cabling to another modem that can provide the wifi.

 

Both internal (with the modem in front of the window) and external antenna do the same thing. sometimes connecting to 256 and everything happy, others to 258 and everything goes wobbly.