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.
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.
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.
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.
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:
- Buy a DOCSIS 3 modem (I like Motorola, but buy what you want)
- Buy a router (I recommend sticking with Linksys or Netgear, but choose what you want)
- 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.
- 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.
- Wait for the lights on your cable modem to go solid (except for the activity light), then turn on your router.
- Test your router and make sure everything is working.
- If necessary, disable IPV6 on your new router.
- Once everything is working, go to Comcast & return the lousy unit that they are renting you.
- Enjoy your new equipment that you now OWN and will not be paying a monthly rental fee to use.
- 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.
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.
It would probably cost about the same for me to sell and ship to you as it would to go on Amazon or Bestbuy.
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).