50% signal isn't enough for most things wireless.

Simple things to try:

(1) Since you're trying to communicate vertically, orient the antenna(s) horizontally instead of in their usual upright position.

(2) Try a different channel, if the software permits specifying one. Around here, our microwave oven wipes out two of the wifi channels, so I've just found one that it doesn't interfere with, and told the AP to use that one.

Cheers