@snozski Do you have any links for reading on understanding how DOCSIS works in regards to SNR and power.
There's an excellent pink sticky post of a DOCSIS primer authored by forum demi-god Sephiroth. Some of the numbers on power levels are a bit out against the values that apply with VM (since these vary according to the network equipment used), but if you want to know how DOCSIS works that's the starting point. As a broad rule, downstream power levels need to be no lower than -5 dBmV, no higher than +10 dBmV, with a range across all channels no greater than 4 dBmV. On a gigabit line about half your traffic passes over a DOCSIS 3.1 channel (which can be considered as bonded frequencies used in conjunction with the bonded single frequency channels of DOCSIS 3.0), there's a few good summaries to read on that via the web since Seph's masterpiece pre-dates DOCSIS 3.1.
The more I've learned about DOCSIS the more amazed I have become that it works at all. The complexity is absolutely staggering, and whilst it is a testament to very clever engineers and technologists (and mathematicians), it is now an analogue technology that has been almost perfected as it comes to the end of its days. VM have said they're going to transition from radio frequency DOCSIS to true optical FTTP (XGS-PON) which is a completely different technology, but for the vast majority of VM customers that's 4-8 years away yet.
There's no fine tuning that can be done to make a DOCSIS connection work better - it can be made worse if there's noise or power problems, once in spec there's nothing more. Also worth knowing the vast majority of VM staff and technicians don't know how DOCSIS works - they're trained to use some occasionally very ropey automated diagnostics, and various rules of thumb when it comes to fault finding and fixing. That works most of the time, but means the concept of the Completely Beyond Us (CBU) fault is a risk for a very few VM customers. I seem to be in that place at the moment, with appalling reliability of my 200 Mbps connection.
Problems with gigabit connections seem proportionality more common than for other speeds, but if everything is working as you want, then don't get wrapped up in the technology and the numbers.