MTD Bridge Utility - There was a problem validating the licence

After trying to licence the utility on a Sage 200 2011 site the following message is reported in the MTD Bridge log.

Client is getting You have browsed from an unrecognized IP address. The proxy therefore denied access to this site or page: http://licensing.services.sage.com/lic/services/LicenceService' http://licensing.services.sage.com/lic/services/LicenceService

Customer IT say there is no firewall in place so what else could be causing this message?

Thanks