@drinkingbird
If you are wondering if DOCSIS 3.0 technology is obsolete, the answer is, yes, and here’s why.
us.hitrontech.com
techblog.comsoc.org
DOCSIS 4.0 capability to more than 50 million homes and businesses before the end of 2025.
Things will be changing sooner than later in the realm of CABLE. D3.x won't support Full Duplex which is where things are going with D4.0. This will level the playing field with Fiber deployments.
DOCSIS 4.0 will bring even faster speeds to your cable modem
www.tomsguide.com
See pic below @
https://www.snbforums.com/threads/modem-router-combo-recommendation.83098/post-817876
The big issue with Cable has always been the upload speeds. 200mbps is nice with D3.1 but, the highest offer with any cable carrier is ~50mbps and usually only on gig plans or higher. So, if D4.0 is coming in less than 2 years it's best to have at least D3.1 since when they flip the switch you might be lucky and get 4X the upload speed for free vs being stuck at 30mbps under D3.0.
At one point Arris was the go to for modems as they preformed better and had less issues to call in about to get them fixed. Motorola stole their cake though and then as mentioned got eaten by Arris.
https://pickmymodem.com/approved-modems-for-xfinity-internet-service/ -- good resource for a quick glance but, there are other options out there if you need higher speeds on the modem side like the 2.5ge ports on the higher end MB/SB models. AFAIK there isn't any modem option with 5GE/10GE at this point though. 10GE ports will probably show up on D4 modems though since that's projected to be able to perform at those speeds.
For the basis of the OP / splitting CM & router into 2 devices I still stick by MB8600 or MB8611. They will hold their value when it comes time to upgrade again and will be able to be sold competitively to pay for the upgrade to D4. I bought my modem 5+ years ago now and could still get quite a bit back from the cost of it. Pricing has been stable on them since release in the area of $160 and they haven't depreciated like other options. It's a worthwhile investment if you plan on sticking with Cable for awhile. Even a short term is a good investment to save the $15/mo on the rental fee which pays for it in under a year.
The other issue is some of the Arris SB series has/had issues with the chipset they were using for awhile.
Intel Puma 6 was a chipset with a hardware flaw used in many cable modems. The defect leads to latency spikes which cause slow loading speeds. It interferes with video streaming, video gaming, and browsing web pages. The defect causes intermittent issues. Sometimes your internet will work fine...
networkshardware.com