Guess this is an old thread, but I couldn't find any good answers out there myself. I eventually found a solution that worked for me. It turned out my wireless router was set to the old WPA, TKIP encryption, but was working ok with wireless clients that had a mixture of WPA and WPA2 setups. I had set the printer (a Samsung ML-2955DW) set up with WPA, but the WPA2 clients would not be able to connect to it, except for a brief period after being powered up.
The solution was to just switch the printer, and all the client settings, and the router over to the newer standard, WPA2 AES. After that, no more timeouts and everything is working fine.