cable modem restart - Time Warner Internet

This question is about "cable modem restart", with Time Warner Cable internet and apps. I have read many, many questions and answers on T3/T4 time outs and they always lead to a hardware problem.

What about T3/T4 errors and no hardware errors? That's a Spectrum tech coming to my house with his little black box. He found nothing wrong with co-ax and looking over my shoulder at my own modem saw nothing wrong with the modem and verified that the signals on the black box were almost the same as my modem. You will want to ask about signal to noise ratio and power level downstream and power level upstream. Are all the channels bonded, etc. SNR 37-38 dBmv. power level plus or minus 1 is 0 . upstream power 43-45 dBmv. at times the modem shows a restart but is not noticed. event viewer on MS platform shows DHCPv6 lost address errors and DNS client time outs and at times DHCP sends a NACK message.

I've been told by tech support that that shouldn't be happening but it is. Oh, and the final kicker or the other shoe dropping. This shows up using two different modems. Arris SB6121 which is mine and Technicolor TC8715D which is Spectrum's.

Does anyone know how to fix a problem that shouldn't exist?

cable modem restart?