After cold reboot for "Update for Internet Explorer Flash Player for Windows 10 Version 1511 for x64-based Systems (KB3133431)" the Bitdefender Firewall blocks all internet access if "Block Internet Connection Sharing" is enabled. Turning off this setting brings back internet access.
This is the only update taken today. (01/06/2016)
Yes, the machine has been rebooted, and cold rebooted a few times before this Windows Update (internet access was OK) and post update as well (no internet).
When the error is happening Windows 10 Network Troubleshooter reports that "One or more network protocols are missing." It cannot fix the problem.
I do not know when Bitdefender was updated. It is set to automatically update, which it does. It is reporting that the latest is installed back at least a few weeks.
Currently running Bitdefender Internet Security 2015, Build 19.5.0.284.
Network for this machine is hardwired (not Wi-Fi). None of the machines on the home network use Internet Connection sharing for Internet access, and so far none of the other machines running Bitdefender has shown this issue. Those other machines, however, do use wi-fi for access.
No way for me to know is this is a Bitdefender issue or Windows 10 Update issue.