SYSTEM SLEEP SLUGS WIFI CONNECTION

Ummm ..... well, you're right, and it would have been very convenient if any of the ones listed, or any of those listed on the other threads I had already checked through, offered any help.

None did.

Anyone have have any specific avenues or suggestions, under the assumption I don't need help in using Apple Discussions?

WZZZ, thanks for the tries, but they didn't really work for me. The first one, about essentially re-starting everything having to do with the network, does provide relief in a way, as it led to a quicker way of getting things going again, but provided no long-term solution. The second didn't apply as it's not an IPv6 issue, not browser-related at all; every function relying on the wifi connection, be in Mail or the App Store or (until recently) iDisk accesss, gets slammed in exactly the same way.

To review: The Wifi icon in the Menu Bar shows full connectivity at all times, and other systems on the same network are having zero problems at the same time that the iMac/Snow Leopard combination have been ground to an essential dead halt. You actuallyare connected at this point, and if you're patient you can see things load.

New Twists:

• In the spirit of playing around last night, I found multiple entries for my home wifi network displayed under the "Preferred" section of SysPrefs > Network. Thinking that looked strange, I deleted all but the top copy of it.
• This morning, on waking the system from sleep, and finding it in its normal sluggish state, I did get a splashscreen popping up to inform me that none of my preferred networks were available and inviting me to choose one from the provided list (and sure enough, at that point the wifi fan was greyed out in the Menu Bar). My network was still listed: I clicked on it, Keychain filled in the password, and everything came back to life and at full speed.
• It appears (this had been previous reported in various threads and fora) that another possible 'quick fix' for this condition is to use the Wifi icon to turn Airport OFF, then back ON ... and system speed returns. This is faster than logging out of and back into the User Account, which is itself faster than doing a complete re-boot, so it's welcome news.

Of course, it doesn't explain why this just started happening or what is causing it. Absent any definitive answers, and not willing to take the more extreme steps like trashing .plist files all over the place and going through the PITA of re-entering all of the configuration details and preferences, this in the hope that some part of what I'm doing will fix whatever it was .... I think I'll just coast and live with this until Mountain Lion is released and I upgrade to that and move into that whole iCloud thing.

Okay, that's some more wrinkles in the grey matter. I'll try the IPv6 thing, then, when I get back this afternoon. No time now. I guess it could be that, but for sure it's not router, as logging into/out of User Account shouldn't be doing anything to it.

OTOH, I've clearly been wrong before .... 😐

Updating, while continuing to play around with this:

It appears as though shorter-term periods of sleep don't have the same effect; if only asleep for a short period I can often wake it up and things will be working normally. Anything over an hour seems to kill the wifi for sure (caveat—not completely tested or verified).

Not sure whether this data point adds anything or not, but thought I may as well toss it out there.

Success! After another day of playing around with this it appears as though the problem has been knocked down, at least for now. I didn't approach things in such a way as to know precisely what the fix was, but the last things that I tried included the following:

1. I played around with the settings in SysPrefs > Network, cycling settings back and forth (changing then changing back, removing and then adding again, etc.), and
2. I installed a firmware update on my Airport Express, which itself involved a bit of a troubleshooting exercise to discover why it wasn't appearing in Airport Utility, and
3. I un-installed SugarSync, which I wasn't using but which was continuing to thrash about and do things whenever the system awoke from Sleep.

At the end of those three things being done, the problem no longer recurs. I have no idea which one, or which combination of the three, served to be the fix, but that doesn't bother me all that much. Things turn out like that all the time. And, of course, it may re-occur and I'll be right back to futzing around it every time.

Thanks to all who responded. Now I have to figure out how to mark this as 'Completed' without giving myself points ....

And .... sure enough ..... it's back!

After about a month error-free, the system's back to doing exactly what it did before. Nothing has changed, no new upgrades or updates, nada; it simply slugs the wifi down as soon as it goes to sleep, and needs a log out&in (a quick process, thankfully, in SL) to get things rolling again.

I played around with Quick User Switching, curious to see if just doing that would do the trick but, unfortunately, it didn't.

I guess I have to go back through everything again, keep futzing, see if something might change. In the interim, keep the system awake for longer periods of time and live with the requirement for the quick logging reset at the start of the day.