The ability to port forward depends more on your wi-fi router and choice of VPN than your internet service provider.
If you’re using an Xfinity Gateway, which is Comcast’s branded router, check out the official tutorial. Otherwise, you’ll have to consult the instructions from your router’s manufacturer.
Some VPNs support port forwarding, which will bypass whatever port forwarding settings you have on your router. Check out our list of the best VPNs for port forwarding as well as more details on how to set it up.