Staying connected to net

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Have the WNDR4000. Works great most of the time on a number of devices.
On an iPhone, Windows PC, Windows laptop, and DTV DVRs, connection is quick and permanent. On 2 Android phones and an Android tablet, connection is quick (sometimes) and the connection is sporadic. For the Androids, connection and last 5 minutes to an hour before terminating - don't know why.
To reconnect, I have to stop/start wifi or change wifi networks and even then connection works ~75% of the time. Again, connections don't terminate on Windows devices.
I can connect my Android devices to other networks (e.g., Sam's, Starbucks) and have no connection problems, thus my suspicion the Netgear router may be the culprit.
I have no idea how to troubleshoot. I've upgraded to most recent firmware. No improvement. FWIW, Netgear Genie shows connection by WPA-PSK but I have the router set (I think) to WPA-AES.
Any ideas?