Port Forwarding not actually opening ports

I would have replied here, but it was closed for comment...

https://forums.xfinity.com/conversations/your-home-network/port-forwarding-not-actually-opening-ports/62257c232aad694bede1d5e9

If you are attempting to forward ports on a Comcast gateway, without luck, then try disabling the firewall (and then perhaps try reenabling it). It seems the gateway is forwarding the port, but failing to create a proper firewall rule.