Recurring Problem I have noticed with connecting to two networks

I am posting this because I have seen a recurring trend in some Win7 computers. Not all, but some. No one has a clear answer, but they all say they fixed it, whether by rebooting, buying a new router, etc. and because the information is so inconsistent my goal is to try and ascertain the true cause of this issue so no one else has to spend the enormous amount of time I have over the passed year trying to figure it out every time the problem rears it's ugly head again and again.


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I have noticed first-hand, and through many forums, a recurring problem with a computer connecting to two different networks causing the computer to connect only some programs to the internet or prevent all programs to be unable to connect.

They conflict with one another and no one I have talked to or seen on forums has a straight answer as to "Why". Some say it's drivers, others say that it's their hardware itself, others say the router is to blame, others say its a physical networking issue, one thread said that it is the Bonjour service (unlikely in my opinion), and some say that it's an error on the users part that they have some settings set incorrectly somewhere. Basically no one has a clear answer as to what causes it.

I have seen this issue only on Windows 7 computers (both 32 and 64bit of varying types like Home, Professional, etc.) and all on different computer manufacturers (it has happened on my Sony and I have seen it happen on HP's, Dells, and others). On many occasions the problem will allow internet to the user's web browser but block the email software (Outlook, Windows Mail, Thunderbird, etc), OR visa versa.

What I know for sure is that one of the networks is the real network and the other seems to be a "imaginary" network created for unknown reasons, and programs become confused as to which one to use and sometimes (or every time) connect to the "imaginary" one.

The only fixes that have worked for me are the obvious Shut Down > Reboot and Disabling the Network Adapter itself through the Device Manager.

All I can theorize about it all is that it more seems to be a software issue than hardware due to the fact it has happened with many different hardware configurations.

Please if you have any information on this issue, or have a fix that has worked and sustained its stability since it was performed, please post what you know.

Also, please do NOT ask for computer configurations and screenshots unless you are referring to one another, I have done thorough investigations of settings and configurations of all the computers and nothing is consistently troublesome to where it forms a pattern.

Pretty much any active secondary NIC can cause this problem including the now famous Bonjour service which installs with iTunes.

There is also another problem where a secondary default gateway is created with 0.0.0.0 being the incorrect default gateway address. This one requires that you type in the actual default gateway into the IPv4 properties in order to connect with the router again, though I believe this is a router problem it happens quite often.

I've seen the Microsoft virtual WIFI miniport cause this problem on many occasion. I've seen Hamachi do the same thing, just a couple of days ago in fact. I've also seen many other types of virtual adaptors cause this problem also.

For what ever reason Windows 7 seems to get confused as to which NIC is the correct one to use for the internet connection. I've personally have helped people fix these types of problems on countless occasions. Still I have no idea what the actual cause is.

As you found out, simply disabling or uninstalling the secondary adaptor fixes the problem.