Q: Installed Lion, now cannot connect to internet!!!

Disabling AVAST Web Shield worked for me too! I'm feeling much better now and thankful that I have multiple computers at home so I could go on-line to find a solution to the problem.

Dave

Same problem. I am desperate. How apple let these happens ?

If you want to talk to an Apple support rep you need to call. They typically do not answer questions here.

Choose the appropriate phone number from this page.

@swingman, yes, I've tried everything listed in this thread. I have made a new settings location and tried manually and automatic DHCP. On the phone with Apple now, as there isn't much from this thread working for me. I will post back if they have a solution.

If you've tried everything listed above you might want to give this a shot.

Open Finder

Go into Macintosh HD

Open the /library folder

In the library folder there should be another folder called "Preferences", go into that folder.

In the Preferences folder, look for a folder called "System Configuration"

Drag that entire folder to the desktop.

Restart the computer.

on restart your computer will create the system configuration folder. 

I had the same issue. No Internet connectivity via Wi-Fi or Wired Network. I was able to connect to all my servers on the network without issue. I removed Avast, rebooted and got the internet connection back. Thanks to the one who suggested it.

Here's what I think my problem is. System profiler says the router is on channel 7 but when I go into the interface on 192.168.100.1 it says it is on channel 3 for download and channel 2 for upload. I can not change the router how could I change the channel in osx?

Scratch that, that was another router, the one I'm trying to access is a dlink Dir-615. I'm in the interface but am on my iPad so I can ot update the firmware which is what I'm sure will fix this cause it's from 2007. Any other thought on what I might also would be appreciated.

I reseted time capsule. Erased all locations on network setings. Turned off everything in my house that works wireless like, Wii, PopcornHour, airport extreme(tha was amplifing my network).

Them I instaled again from the begginng Lion and now it is working. Thanks for your help !

No idea why this is the case but Aaron260s suggestion works.  You have to leave the System Configuration file on the desktop however. 

I got far too excited far too soon. Same problem again this morning.

I just spoke to Apple support. They said there's no known issues with internet connectivity/dropping. People need to officially log these issues, I think.

They had me do the usual, ping; unplug the computer from the back (not just the outlet) for 20 seconds, restart, shut down, restart again, immediately holding down Command Option P and R until the Apple chime chimed twice. Which apparently resets, um, stuff. Whether this has a positive effect remains to be seen.

I'm seeing this also. In my case, it's my ethernet interface that isn't working right while my Wi-Fi interface works just fine. In both cases, I'm connected to an Airport Extreme that's using a cable modem to connect to the Net. The ethernet interface shows as connected (green dot), and it fetches the correct IP, DNS, etc. via DHCP, but I can't connect to anything. In fact, I can't even ping the ABX's gateway address (no route to host). I can, however, access the ABX admin interface via Airport Utility.

I tried removing and recreating the interface to no avail. I also tried playing around with the service order to see if that impacted anything, but to no avail.

This is on my 2007 Mac Pro.

The problem may be related to Avast, if you have it installed. To resolve the problem Avast's mail shield and web shield must be disabled. This problem seems to be related to the way inwhich Lion handles packet forwarding.