This may be a bit long so bear with me.
Problem: I have a new iMac desktop computer. When it goes into sleep mode and I leave it for quite a while (more than two hours) and then I wake it up, the computer does not automatically connect to my WiFi.
What I'm using from Shaw: Cisco DCP3825 modem/router combo.
Location: Both the iMac and router are on the same desk about one foot apart. There are no other electronics in the room except for my Canon printer that has WiFi. Most of the time it is shut off. There is no telephone, baby monitors, TV, stereo anywhere close to this room.
What's been done so far: Since I have Apple Care I thought I'd contact them and make sure there was nothing wrong with the computer. Trouble shooting started via the phone without success. Many different things were tried. I was passed on via phone to a senior Wireless supervisor who ran me through the same procedures again without any luck. She then had me run diagnostics on the WiFi system which ran while I let the computer go to sleep overnight and then waking it up, it didn't connect and a file was created. She then had me e-mail this file to one of Apple's engineers. After waiting a couple of days she called and advised that the only thing they could find wrong with the WiFi was that there were two or three WiFi networks nearby that were using modems not designated for use in Canada, this she said may cause interference with my network. However to check this she had me take the computer into the Apple store in Winnipeg and left it with them to test it on their WiFi system to see if they could duplicate the problem. They could not, the computer connected from sleep without a problem. After making sure I had backup for my system they decided to do a complete new install in case there was a software conflict. I brought the machine home and after getting up and running I still had the problem.
To connect from sleep mode I have to turn off the WiFi then turn it back on, the computer searches and connects without any problem. Also we have a Mac Book Pro used downstairs that has no problem connecting from sleep mode. The iMac has no problem connecting when rebooted or started from a cold boot. Any helpful information would be appreciated. As an aside the customer service at Apple is top notch.