Upgraded my wife's iPod Touch4 to 5.0.1 and lost my internet connection (home Wifi). My iPhone4 (5.0.1) continues to work. Have "restored" and reset network. Spent time on the phone with Apple. Ended up with advice to go to an Apple Store. Software glich suspected.
Option suggested: Restore, then create name for the iPod. That will remove all software. If all works, restore Apps and data only.
Have not tried this because I am not sure how to do so and my wife would be unhappy if I lose her data!
I contacted D-Link by email and the problem is solved in < 24 hours. Would have been faster but I had to sleep last night and had to work today.
I upgraded to a new firmware -- just a week or two old. I set up the wireless network with a new password. The iPod Touch with iOS 5.0.1 now works just fine, as do all of my other network devices.
D-Link is the best -- I am using a D-Link DIR 655 Router.
Thanks to all who offered advice.