If you have experienced issues connecting to Windows 2003 Servers and other Remote Desktop hosts, or connecting to Citrix sessions from Windows Vista there is a solution you may wish to try.

For an excellent post on the why's and wherefores of the issue see this post from Tom Keating. For more on the Citrix issues see this thread from the Citrix support forums.

The short answer is that the TCP Stack in Vista supports automatic receive window tuning, and this appears to result in connectivity issues in certain situations. The fix is to disable autotuning by running this command as an administrator. (Followed by a log out/log in cycle).

The following is copied directly from Tom's blog post.

- Run a command prompt (cmd.exe) as an Administrator
- Type: netsh interface tcp set global autotuninglevel=disabled
If you want to to re-enable it:
- Type: netsh interface tcp set global autotuninglevel=normal
In some cases you may need to use this command in addition to the above, but I didn't have to:
- Type: netsh interface tcp set global rss=disabled

Now be aware that this will turn off auto tuning on all connections, read Tom's article for a good explanation of how this might be prevented and the possible consequences. I can attest to the fact that it resolved a number of connectivity issues I was having.

Thanks to Mike DieBold of the Kentucky Retirement System for pointing this solution out to me!

Cheers,

Robert Porter