Remote file does not exist -- broken link!!!

hello all

so we have a 2 virtual web appliances both running 4.3.0.2 that are managed by a SM200 unit.   for a specific web site one of the units connects okay the other comes back with a 403 Forbidden message

HTTP request sent, awaiting response...
HTTP/1.1 403 Forbidden
Date: Thu, 26 Jan 2017 14:18:34 GMT
Server: Apache
X-Powered-By: PleskLin
Connection: close
Content-Type: text/html
Remote file does not exist -- broken link!!!

When I connect from the working unit I get 

HTTP request sent, awaiting response...
HTTP/1.1 200 OK
Date: Thu, 26 Jan 2017 13:58:25 GMT
Server: Apache
X-Powered-By: PleskLin
Connection: close
Content-Type: text/html; charset=UTF-8
Length: unspecified [text/html]
Remote file exists and could contain further links,
but recursion is disabled -- not retrieving.

We have tested access to the site from the network that the faulty unit is connected to, is there anything obvious I can do to resolve this?

I have been unable to get hold of Sophos support via phone ( 2 hour in a queue so far ) and logged an incident via the webpage but so far no acknowledgement of this

thanks in advance