Ya, really feel that your area in so congested with 2.4Ghz radio that the poor router and devices are having a hard time trying to keep the connection.
One thing you can try if you haven't already, lower the power out put from HIGH to say Medium on the 2.4Ghz radio and see if by making the broadcast foot print smaller, maybe it might help keep the signals near you or in the room better for you.
One other thing you can do to make sure the router is working as I feel this is not a HW issue, I would take this router to a different location, where there are
fewer WiFi routers around and check it out. Maybe a friend or family. I bet you the router will work better.

One think you might try, might have to see who has the wifi near you and talk to them tactfully and explain to them that everyone's radios are causing interferences. Ask them to see if you could work out some channels and power settings for each one. I know this is crazy however you could talk to them about maybe combining your wifi access. All of you are is such close proximity, why not have a collective wifi and share the access and cost. You could all have the same SSID, just be on different channels. At least see if some of the near by router owns would be interested. Would really help everyone on the 2.4Ghz band. Just a suggestion.
Keep us posted.