We've run into strange issue on the freshly installed servers. H/W: IBM server X3550 M4 7914; OS: Windows Server 2012 Std.

Then we try to browse on the servers thru IE, not all sites are opened or it takes too long time to open the page, i.e. very few of them can be opened.

Local FW are disabled. Servers are in a new subnet and traffic is allowed for it. VLAN is configured properly Another Windows Server 2012 host is running OK and Internet access works fine, but it is VM running on Hyper-V 2012. No proxy is used on the network.

At the same time, if one tries to establish telnet session to any site on 80/443 ports - it does work. Google works as well.

I've tried to configure single Qlogic adapter to check if the issue remains - it does. Teaming is configured with the means of QLogic, not by built-in functionality.

IE Enhanced Security is disabled. IE settings were reset, more than once.

Why would certain sites work while others not - Idk.

I also tried to disable ecncapability and restart server - no luck

netsh int tcp set global ecncapability=disabled

Any thoughts?

UPD1

VMQ is disabled. Servers are not running Hyper-V.

UPD2

Servers were rebuilt from scratch, got a mail a few mins ago. Issue still remains. Teaming is now configured with the means of Windows Server 2012.