Hi Shaun,
Do you ahve access to the switch? If so, I would check to see what the PVID "show vlan ports "of the port is, make sure that all required networks are configured on the trunked uplink port "show config vlan". Also, you can run the command "show policy" to verify that it is not configured on the switch.
If there is anything else you would like help to see inside the switch, let us know 🙂