As my organization started to upgrade our domain-joined workstations from Windows XP to Windows 7, we ran into an issue with the clients browsing via DFS (Distributed File System) and file transfer speeds both over the LAN and the WAN. As the users explored the DFS tree, the navigation was extremely slow, sometimes in excess of 20 seconds drilling down just one directory level. Likewise, the file transfers were also very slow between the Windows 7 clients and the back-end Windows 2003 servers. The users were not happy. To make the problem even more difficult to troubleshoot, it was intermittent in nature. After looking at all the more obvious possibilities and ruling them out (Antivirus, network congestion, server issues, GPOs) we stumbled upon a solution that worked in our environment. On each client workstation, we ran the following command:
netsh interface tcp set global autotuninglevel=disabled
Once set, we rebooted the workstations and the Windows 7 clients were able to browse the DFS paths at normal speed and file transfers got much better. The default tuning level is “normal”. Other possibilities include disabled, highlyrestricted, restricted, normal, and experimental.
To view the current setting, type the following command:
netsh interface tcp show global
After upgrading the back-end servers to Windows Server 2008 and Windows Server 2012, we were able to put the auto tuning level back to “normal”.