Q: After Lion upgrade, having network issues after wake from sleep

Having exactly the same problem using the airport functionaities of my time capsule since the update to lion.

Excatly same problem. I also have an extended WIFI network, from TC to an Airport Express.

If I run network diagnostics, I can connect again, but I dont want to do that every time my mac wakes :/

+1 on the network connectivity issue.  Looks like this is some kind of a bug in 10.7.  I'd suggest other people experiencing this issue fill out a Bug Report here--

http://www.apple.com/feedback/macosx.html

--so as to make Apple aware this is a problem affecting a number of users.

Same problem here... going to try a fresh install to see if it fixes it.  This is why I HATE upgrade installs.

Just updated my Airport Extreme, issue still persists.

I was already running 7.5.2 on my Airport Extreme prior to upgrading to Lion, so that's not the issue for me either.

Ok, I've narrowed it down to my external USB 2.0 WD drive I use for my Time Machine Backup. When unplugged, the internet connection works perfectly after sleep. I don't know if its the drive type or the fact that its an external time machine drive, but I hope Apple fixes this.

It's definitely linked to Time Machine and backups.

I think If I put my machine to sleep/close the lid and Time Machine happens to be performing a backup, when I open the lid again, the network connection is lost and I receive a bunch of errors about the backup disk being unavailable. 

This means that if my mbp isn't in the middle of a backup when I put it to sleep, wifi comes back up without a problem. 

Just came in to report that I'm having the same issue.

Same problem on my Early 2008 13" MacBook.  Turning Time Machine off made no difference.  No issues on my Late 2009 27" iMac.

I am able to restore connectivity by toggling wifi off and on.  But that's obviously not a fix.

I've been doing the same.(toggling wifi off and on)  It's a fix, but not a permanant one.

Same issue here.  I run diagnostics to fix, which works, but is more than a little annoying.

I have exactly the same issue using a wired GigaBit network. Looks like a bug to me...