I have Bitdefender and there I turned off the "firewall" and it suddenly worked.
Hi!
I had the same problems with Bitdefender, the firewall didn't allow it to go online, so I contacted Bitdefender's support, and they gave me this solution to fix the problem:
To troubleshoot the encountered situation, please follow these steps:
-open Bitdefender
-click Protection
-click Settings under Firewall
-click Settings again
-set the Default Application Behaviour to Allow
-set the Network Adapters to Home/Office.
Thank you thank you thank you!!!! This solved my problem after two and a half months of failures!!!!!