The ProxySG appliance sends the X-Bluecoat-Via header is to detect loops in the network. However, because some upstream devices do not like this header, you will need to install policy to remove this information from the header.

For information on the X-Bluecoat-Via header , please refer to 000016702

Install the following CPL rules in local policy. 

<Proxy>
action.ControlRequestHeader(yes)

<Cache>
action.ControlRequestHeader(yes)

define action ControlRequestHeader
delete( request.header.X-BlueCoat-Via )
delete( response.header.X-BlueCoat-Via )
End

For step by step instructions on installing the local policy file, please refer to 000010101