You might also consider
'better' antenna like some of these, but I'd caution that "better" is completely subjective.
Like the above consideration for the PowerLine units, I prefer to buy these locally because, if they don't show an immediate improvement, then I return them for a quick and easy money-back.
PowerLines are nice like that. Plug one into a wall-socket (NOT POWER STRIP!) near the router and run a cable to it. Then plug the Receiver PowerLine unit into your room's wall outlet. If it's going to work, it might take 3-5 minutes to sync-up. If the 3 lights never come on, well, that's it - it's not going to work. Take the kit back to the store for a refund.
Antenna are the same way. Power down everything, replace the antennas on one unit, then another, power everything back up and see if there's an improvement. Sometimes twisting and turning, or moving the antennas around can help a bit. But the improvement won't take long to display, or they won't at all.