Call your ISP. You are getting knocked off because of the Upstream. Mine was actually just doing that. 55 is the breaking point. Theoretically, you want it under 48. Your downstream should also be higher. But then again, I do not know if you are addressable or intradicted or how your stuff is wired.
My modem was getting knocked off when it jumped to 56. When it was on, it stayed at 55. After they replaced out the drop (wire from the tap to the ground block), it dropped to a 42.
Call your ISP and tell them your modem is getting knocked offline and they should be able to figure it out from there. If not, tell them you know a cable tech from an online community and he said the upstream is fucked. And "you are dropping offline with maxed out levels."
The good news is that your Signal to Noise ratio is excellent.
