Could be there is some interference... Have you tried setting the channel manually, to a less used channel? You could check how much activity is in the area on the 2.4 GHz.
Use your laptop (disconnected from your network to improve scanning-results) with a tool, called INSSIDER (
link here), to see what else is happening, and which channels are less used.
Most of the time a very strong signal in your neighbourhood may interfere with your connections dramatically.