This article applies to:
- WebMarshal
- Microsoft Windows Server or Workstation
Symptoms:
- One or more sites time out when using the WebMarshal proxy, but they load fast when not using WebMarshal
- WebMarshal is installed on Windows Server 2008 or above (or related Workstation OS)
- The behavior is not changed by adding the sites to the bypass list, disabling all connection rules, or disabling the cache
- WebMarshal on Windows 2003 server in the same LAN works well
- In a packet capture it appears that the sites refuse or reset the connection
Causes:
- This issue could be caused by the "TCP auto tuning" feature of networking in recent Windows operating systems.
- Auto-tuning is known to cause communication issues when used with devices that do not support auto-tuning. The Microsoft article (referenced below) states in part:
"When the Receive Window Auto-Tuning feature is enabled for HTTP traffic, older routers, older firewalls, and older operating systems that are incompatible with the Receive Window Auto-Tuning feature may sometimes cause slow data transfer or a loss of connectivity."
Resolution:
To disable TCP Auto-tuning:
On the WebMarshal node server(s), open an elevated command prompt and run the command:
netsh int tcp set global autotuninglevel=disabled
Notes:
For more details of the auto-tuning functionality, see the following Microsoft Knowledge Base article: http://support.microsoft.com/kb/947239