We have had this problem for over two weeks now. They replaced the line to the house, the lines under the house, and the modem. The problem has not gone away. We are giving up and going to switch back to our last provider. It was the worst decision for us to switch to this provider. They just can't get it figured out.
They don't know how to configure/route the mess they have acquired, they are trying to access 3 different DNS servers& the emta server by horribly different pipelines thru widely varying routes and propagation delays which fouls up reliable packet transfers via the 3 different modes. It either overloads or confuses/times out the all in one causing a reset.
Sorry but the IPv6 & emta phone issue is a known bug going on 3 years now. The only solution if you really need IPv6 is to add a splitter, buy your own modem for the internet side and if you're a twc legact customer, they drop the modem rental fee.
It's also possible the technicolor combo works better, the Ubees are junk