When in doubt, cheat.
You can use a Ubiquiti Nanostation M or Nanostation Loco M (smaller, cheaper) as a bridge between Ethernet and the wifi network. Those are 802.11n devices - the M2 is 2Ghz, the M5 is 5Ghz.
Additionally, they have very good directional antennas for the price, so you'll get a much better signal with them than your laptop's built-in antenna, though you'll have to point them at the AP.
So, your side is
Your computer <--- ethernet cable ---> Nanostation <---- wifi ----> AP
In particular, to set this up
Station mode
AirMax is OFF (it's not for talking to a normal AP)
"Lock to AP" is the option to bind a specific AP's MAC address.
- Don't try this first; first point the Nanostation at each AP in turn, to find the one with the best signal, and then simply point it at the correct AP; the Nanostation's directionality may be enough to stop the roaming.
Turn down the Nanostation's output power; it's going to be far more than is needed, and may actually cause problems due to reflection or overpowering the AP's receiver.
Be warned; the current batch of Ubiquiti AirMax AC gear is not for talking to consumer 802.11ac. The M series, however, talks to normal 802.11n just fine.