All apple products de-associate themselves from the router when they are on standby to conserve battery. If that's what you are referring to being disconnected, it's normal.
Thanks for the info, but I'm fully aware of this behavior. I do not need to check the router to know that Safari has an error screen telling me that there is no connection to a network while I am actually using the device to browse the internet.
If you read my posts, you will notice that it is all my wireless devices that are having trouble, including my Asus wireless bridge. My Libratone wireless speaker also keeps getting thrown off the network, and needs a power-cycle to restore connectivity.
This behavior has started with me installing Beta 3. This is the first time that I have experienced this with any of my network devices ever since owning the Asus router. I had to got back to 23b, which uses the same settings that I used with Beta 3, so that can be ruled out.
Hope this info helps.