If the UTM. Is the DG and you configured transparent proxy all should work fine. Be sure your LAN network is mask on your WAN interfaces and no http or https is allowed through packet filter rules. Then all should work fine.
If the UTM. Is the DG and you configured transparent proxy all should work fine. Be sure your LAN network is mask on your WAN interfaces and no http or https is allowed through packet filter rules. Then all should work fine.