For us in CT - 2014 was the issue - Frontier bought out the AT&T assets in CT. I had AT&T Uverse for phone/internet. When Frontier took it over, it was an abject disaster - ended up having to go back to Cablevision - which I swore on my life I would never do. Optimum, however, has turned out to be a great product. I've never heard anyone say anything good about Frontier.
The Frontier folks said that AT&T screwed them in the transition, but who knows.