Windows 10

And I have popcorn)))

Microsoft does a great job breaking things,which is why it's a good idea to only support a final build and not beta builds.Huge waste of resources.Microsoft breaks so many things along the way.There are quite a few other a/v's which have firewall issues with win 10.It also doesn't help that in most cases I've seen,Windows Defender remains active on win10,even when installing an a/v,which can cause some issues in and of itself.For those who have that issue,there are several ways to disable it.I find group policy editor to be pretty easy to do it.

1.Press the Windows key + R to bring up the Run box. Type gpedit.msc and hit Enter.

2.In the left pane of Local Group Policy Editor, navigate to the following location:

Computer Configuration -> Administrative Templates -> Windows Components -> Windows Defender

3.In the right panel you will see a policy labeled “Turn off Windows Defender“. Double-click on that policy and set it to Enabled.

I had to turn off the BD firewall to get internet connectivity

I came here to report the same issue. I have NO internet at all (Error says can't connect to primary DNS server) - with the Total Security 2015 Firewall turned on, but when I turn it off it works fine.

I had to uninstall and reinstall the Bitdefender program after my Windows 10 upgrade and it worked fine until restart. After restart is when the problems started. After second restart no internet at all as long as the BD fw is turned on. It couldn't even detect the many wifi spots in my area.

Oh, and also: I attempted to try the fix for the Windows Defender issue mentioned by white_chocolate above and it appears gpedit.msc is not found in Windows 10. *shrug* I thought I might have a chance of fixing it that way lol Thanks for the suggestion though! I will poke around and see what I can find for Windows Defender though, just in case that is an issue here.

So, I had this issue and suspected that BD Firewall was the cuplrit. So, I did some testing and investigating. In Bitdefender 2015 Total Security, go to Protection->Firewall->Adapters. You should see the current adapter (my computer has two ethernet cards) that is connected to the internet. You will also see this:

Make sure that "Stealth Mode" is set to off. I have to do this every time I restart. YMMV

I saw a mod give this solution. Another workaround would be to deselect the Block Internet Connection Sharing option from the Bitdefender Firewall. Cheers!