WiFi Calling not working - Comcast gateway

edwardp

    I previously posted a thread about WiFi Calling not working when the phone is connected to a Comcast (Arris) gateway and I believe I have since found the reason why. I was unable to locate the original thread.


    When the Comcast gateway provides the IP address for the connected device either via LAN or WiFi, it will provide both IPv4 and IPv6 addresses to the PC and/or mobile device. When the phone (in my case, an LG Leon) receives only an IPv4 address from the gateway, WiFi Calling connects successfully each and every time. I am using an older Cisco Linksys router configured as a switch, it's latest firmware is from 2013 and it only receives IPv4 addresses from the Comcast gateway.


    If the phone receives an IPv6 address from the gateway, WiFi Calling doesn't work at all.


    According to Wi-Fi Calling issues the IP addresses for WiFi Calling are all IPv4, not IPv6. I tried a different router model also configured as a switch, but it provided both IPv4 and IPv6 addresses to the phone and WiFi Calling did not work. I suspect that the phone software or perhaps the APN is priroitizing IPv6 over IPv4 when it receives both types of addresses.


    If the router/switch is IPv4 only, WiFi Calling works fine. Otherwise, it doesn't.


    The best way to remedy this, at least with a Comcast gateway, is to put the gateway in Bridge Mode, which turns off the radio, it may or may not turn off the "xfinitywifi" hotspot though and use a standard IPv4 router, as a router, not as a switch.






     

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      • tidbits

        Re: WiFi Calling not working - Comcast gateway

        It's the arris. Switch it out and watch what happens. I run my own modems and Arris is one of the worst ones to purchase or get one from providers. They purchased Motorola and their Arris/Motorola SB are better than the rest of the junk they sell.

          • e2k

            Re: WiFi Calling not working - Comcast gateway

            I've had Motorola SB modems that have lasted for years without a problem.

             

            I would avoid any modem/router combination that your ISP supplies. Besides, they will typically charge you a rental fee. So they rent you a lousy unit, and you keep paying for it month after month, year after year.

              • tidbits

                Re: WiFi Calling not working - Comcast gateway

                So far from all the modems I have tested the Motorola and Netgear modems work well. The Arris ones have always been trash. Since they sell cheap to providers they often give the Arris ones to customers. I started to buy my own because of it. So far the Netgear one I have had still works like a champ.

            • edwardp

              Re: WiFi Calling not working - Comcast gateway

              If I bring the Arris to the local Comcast office to swap it out, they cannot guarantee I will get one of the other brands, they issue what they have and I'm not sure the outer box (with the information labels on it) specifies which brand is inside.

               

              In doing further testing with various routers, WiFi Calling (with the LG Leon) only works when the phone receives an IPv4 address.

                • e2k

                  Re: WiFi Calling not working - Comcast gateway

                  edwardp wrote:

                   

                  If I bring the Arris to the local Comcast office to swap it out, they cannot guarantee I will get one of the other brands...

                   

                  Correct, but that is not the approach that we are recommending. To be specific:

                   

                  1. Buy a DOCSIS 3 modem (I like Motorola, but buy what you want)
                  2. Buy a router (I recommend sticking with Linksys or Netgear, but choose what you want)
                  3. Go home and hook up your new cable modem directly to your computer. If you cannot get your new modem authorized via comcast's website (it should redirect you there when you try to surf the net), call customer service to get it authorized.
                  4. Once you new modem is working, unplug the power (this is important). Connect the internet port of your router to the cable modem and plug the power to the cable modem back in.
                  5. Wait for the lights on your cable modem to go solid (except for the activity light), then turn on your router.
                  6. Test your router and make sure everything is working.
                  7. If necessary, disable IPV6 on your new router.
                  8. Once everything is working, go to Comcast & return the lousy unit that they are renting you.
                  9. Enjoy your new equipment that you now OWN and will not be paying a monthly rental fee to use.
                  10. When and if you no longer need your equipment, you can sell it or give it to a friend (something you could not have done with the rental unit).

                   

                  In short, get your own equipment and dump Comcast's piece of junk.

                    • tidbits

                      Re: WiFi Calling not working - Comcast gateway

                      I would sell you a Motorola router that I have sitting in my closet. It's an Artist however it is exactly the same Motorola SB141 just white and rebranded since Arris purchased Motorola.

                      • edwardp

                        Re: WiFi Calling not working - Comcast gateway

                        I suspect the issue is, that T-Mobile's WiFi Calling does not work under IPv6.

                         

                        I was at an establishment earlier today and connected to their Comcast gateway using the 'xfinitywifi' SSID. The gateway (Comcast Business) was a Cisco unit. The phone received an IPv4 address from it and WiFi Calling worked perfectly.

                         

                        As far as I can tell, there is no way to disable IPv6 on the Comcast-supplied Arris gateways. Again, if I went out to swap it, there's no guarantee that I will receive a Cisco or Technicolor router as a replacement, the office will give me whatever they have in stock at the time - and it could indeed be another Arris. I have since purchased a T-Mobile Personal CellSpot router. That sends an IPv4 address to the phone and like going through the Cisco above, WiFi Calling works perfectly (under IPv4) with it.

                         

                        As I also have Comcast phone service, anything to replace the Arris would have to be compatible (approved by Comcast).