Problem: When Internet Explorer 6 or 7 is configured to proxy through the Sophos Web Appliance, some web sites do not load properly. When not going through the web appliance, these sites seem to work.
Cause: Certain web sites and various software, including Quicktime and Yahoo Messenger, may require HTTP 1.1 through proxy connections.
In Internet Explorer 6, the “use HTTP 1.1 through proxy connections” option is likely disabled by default.
Firefox 3 does not have this issue, whether it is configured to proxy through the web appliance or not, as it uses HTTP 1.1 with or without going through proxy connections.
Solution: Verify that the “use HTTP 1.1 through proxy connections” option is enabled:
- Exit all Internet Explorer windows.
- Open Control Panel > Internet Options.
- Select the Advanced tab.
- In the Settings area, ensure that the “use HTTP 1.1 through proxy connections” is checked.
- Click Apply and then OK.