I have the same issue, I have to occasionally restart the AP(access point) to get the wireless connection to work again. 

Currently the ap is connected to a 10/100/1000 gigabit switch that is connected to a telstra smart cable modem. 

This is a very simple novice setup that should not be so complicated. 

I'm my opinion the sp is broken and I prob need a new one.....

I have a pc connected to the switch aswell and it's a perfect connection. 

Firmware is up-to-date?

Is the Wi-Fi still visible when that happens? 

Beside your phone, does other wireless device connect?

I have the same problem !!

Firmware is update. My hardware version is V3.

WiFi is visible but it seems to have problem with authentication. After some trying my phone ask me to input the password again.

Sometime after very long time, it gets the connection but not always.

I try also with another phone and tablets, same problem.

As said if turn it off and on again, it connects automatically without problem.

I think that this AP is broke.