I had continuous problems with Frontier when I went from 3 to 6mb. They came out several times and they also tweaked things back at Frontier to no avail. I tried several of their 7550s (the current modem they supply). Then I bought my own Netgear N600 wireless dual band gigabit ADSL2 + modem router. I haven't had a disconnect or any other problem since. That was about 3 months ago.
It's an OEM SKU made to tailor to custom firmware needs. Sort of how the MI424WR routers used on FiOS and other providers are not the same at the heart.