Netgear Modem - Wifi Authentication Issues

We have a Netgear DSL Modem/Router.  We have problems with the wireless connections dropping and can't reconnect.  Sometimes it seems when a new wireless device(iphone, blueray) connects it drops an existing connection.  The laptop can see the network but just can't connect.  Today we had 3 different devices drop connection and the error said the password was incorrect even though it was.  In all cases if we power cycle the Modem everything works fine.  The wired connection stays working and can connect to the internet fine.

Is there a maximum limit of wireless connections and can it be changed?  Or is it Modem issue?