Daughter was just given an old iMac and I cannot get it to connect. Not used a Mac since the mid 90's so I am pretty much lost with general T/S. No other Wifi device in the house is having issues. I've entered everything in correctly. At first it would sit for about 30 seconds trying to connect then come back with connection failed. Changed by SSID to broadcast, it saw the network but still would not connect. Googled the issue, tried running through network diagnostics but issue persisted. Deleted the keychain per one suggestion, issue persisted. Read that others had issues with Linksys routers. I have WRT54GS. Some claimed they fixed it by updating router to DD-WRT. Been meaning to do that for a couple years so I went ahead. Afterwards, it not tries to connect and within seconds it says connection timeout. Changed the channel to 7 per something else I read, issue persisted. I'm at a loss right now. None of my searches have come up with an answer. Old iMac running Leopard. Router using WPA2. Not sure what other info you need.