My Sagemcom F@st 3868 cable gateway (modem-router combo) has four devices on its LAN ports: a PC, a Hardware Firewall, a Cable TV Switch and a VoIP Adapter. The GRC Shields UP! test showed several ports Closed but not Stealthed. I have forwarded all the Closed ports found by Shields UP! to the Hardware Firewall, which has Stealthed them. However, Port 0 is still not Stealthed and there is no way to forward it to the Hardware Firewall. The gateway also has a built-in firewall but even setting it to High does not resolve the issue, probably because the RTP and SIP ports are forwarded to the VoIP Adapter, which requires them to work. Any suggestions for how to Stealth Port 0 will be appreciated. Thanks.