No internet when booting from Windows to OS X

I installed Windows with Bootcamp and have an Airport Express. Every time I boot from Windows to OS X it connects to the wireless network but not to the internet. Other devices still keep their connection to the internet.

So, the only thing that makes this work is to turn Macbook's Wi-Fi off, turn Airport off (!) and turn on everything again.

The same problem also happens when I boot from OS X to Windows, but in this case is easier, since I only have to turn off and on the Wi-Fi.

The problem doesn't happen with my Linksys router.

I'm using Moutain Lion 10.8.2, Windows 7 x64 and I think I have the last Airport firmware version: 7.6.2. I'm using DHCP.

Do I have to click on the Bootcamp tool and chose Restart in OS X... option or can I simply restart the computer using the Start button?

Solution 1:

It sounds to me more like your Airport Express is acting up (since you mentioned that the Mac works fine with your older LinkSys router.) Check for a firmware update via Airport Utility.
Additionally, you can force Windows to release the DHCP lease on its IP address by going in to the Windows command prompt and typing

C:\Users\myusername> ipconfig /release

Just do that before you restart into Mac OS X. I agree with @Buscar that you should try to reinstall the BootCamp drivers (and check Windows Update for any updated drivers.)

Solution 2:

Every time I boot from Windows to OS X it connects to the wireless network but not to the internet.

Windows is not releasing the Internet connection, so try to stop it (turn off wifi) in Windows first to confirm.

If that is the case report it and we will work on next step.

EDIT!!

Great so it Worked!..

At least you do not have to reboot to switch OS :)

Here is what I think is happening.

Since you had installation problems with bootcamp there is a driver that is not Releasing the Internet connection.

Since you can not have 2 Internet connections on one card, that is the problem.

If you want to do some analysis: Try running Netstat in OSX Terminal (after switching os without turning wifi off) and see if it shows it and confirms the theory.

Possible solutions:

1- Turn wifi off in Windows before switching the os.

2- Monkey around finding the specific driver to replace it ?

3- Make complete new Bootcamp install ?

4- Also see this for more information on similar problem