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

It sounds like both of you are not connecting to DNS.

Back to network settings - Advanced - DNS

Does is show a DNS server address and Search Domain?

Sure does.  It's shows the same as the router address. It has always worked before.

My settings show a DNS server, but no search domain... I'm way out of my depth here with understanding what that means.

Have you tried turning WiFi on and off again multiple times?

I have a similar problem which occurs after putting the machine to sleep and waking it. It is eventually fixed (until the next sleep) by following that procedure. It does not work first time every time, mind you.

Hoping for a fix.

OK we found the cause of your problem.

A simple explanation of DNS is that it is a server on the internet that acts like a Phonebook.

Translating names in numbers... When you type www.apple.com it needs to be translated into a IP address that looks and acts much like a phone number.

Without a DNS service you  can not connect to a website.....

Usually the creation of a new network location and deleting the old ones does the trick and forces your computer to reprogram all this stuff. It looks like it did not work.

Possibly your router is preventing the ISP (your internet service provider) to push these settings through.

You can contact your ISP and ask for their DNS settings (check on their website). Or try the Google DNS settings. Unfortunately many ISP's insist in using their settings. So its best to stick with them.

Before doing all this you could bypass the router and connect the Mac directly to the modem. And do the entire power down thing again. Possibly followed by creating a new network location as discribed before.

Once this works you can put the router back in place.

No DNS is not my problem, I also have no access to the router but I know it's working fine.  I even changed it to norton dns and still nothing.

I'm in same situation.

Have reset location, reset SMC, verified DNS is corrent and ping, traceroute etc works from console but seems to be no TCP connection.

All other devices using same router works fine...

Glad it worked

Its really hard to trouble shoot without being present with the system.

For example Manateeman; one Norton or any other "protection" is installed all bets are off, sorry...

GNYF  Create a new user and see what happens.

I have to step back now and have to go back to work...

Will check later

I'm still having this problem. Please see my thread:

https://discussions.apple.com/message/15660995#15660995

Problem solved!

I uninstalled Avast, rebooted and voila!

Thanks - simply disabling Avast Webshield was enough

Thanks!!!!! That worked for me too!