Users are unable to access a website when going through the ProxySG as it uses HTTP 1.1 when connecting to servers (by default) but the browser is able to access the website directly using HTTP 1.0.
In some rare cases, web servers may not support HTTP 1.1. Accessing such sites may require the use of HTTP 1.0 for the content to load. The ProxySG can be configured to use HTTP 1.0 when connecting to specific websites by using policy.
Note: At the time of writing this document, this can only be done using CPL or setting it globally via the command line interface (CLI).
Example CPL policy:
To configure ProxySG to use HTTP 1.0 globally using the command line interface (not recommended since it will prevent the proxy from using the features of HTTP 1.1 - More Information):
ProxySG# configure terminal
ProxySG#(config) http version 1.0