Try changing your beacon interval to 50 ms.
Have a read. Could this be the problem?
I've only been running my Pi Router a few days now. I just had to hard reboot my router an hour ago. I just suddenly couldn't connect to the internet. It's the first time in 3 or 4 days for me and I don't really do "big" downloads, but I do stream videos mostly. I may also lower my beacon interval if it happens again.
Oh, and I don't have any other routers in my system. My Pi Router is my primary router.