sounds like the signal from the cards's antenna is getting blocked. Happens alot, especially if tower is on floor. You will need something like this Buy Wireless antenna,WiFi Antenna,2.4Ghz 5Ghz Wlan Antenna,RF connector,RF pigtail cable,Lightning Protector,802.11 a/b/g, Omni ,panel ,yagi ,Grid antenna

Doesnt need to be exactly this but similar. You will also need a length of cable to connect the two