One of the first things I would check is the signal strength:
You should see something like:
Code:
wlan0 IEEE 802.11abgn ESSID:"nixcraft5g"
Mode:Managed Frequency:5.18 GHz Access Point: 74:44:44:44:57:FC
Bit Rate=6 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Encryption key:off
Power Management:off
Link Quality=41/70 Signal level=-69 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:28 Missed beacon:0
The "signal level" (here, -69dBm) is the important number. The higher it is (less negative) the better. If you see it's in the -70's, you may need to reposition.