If Comcast's new DOCSIS 3.1 service is used, the link between...

https://litecomparison.com/motorola-mb8600-vs-mb8611/

The MB8600 model is built for the future. To get the best speeds, it should be used with a router that also supports Ethernet port bonding. This is because it supports Ethernet port bonding for very high speeds, or speeds greater than 1Gbps. They don't yet have those service tiers or routers. Soon, though, they will be. Until then, you can use any router. The amount of wireless technology you have will be up to you. An AC1900 wireless router would be able to do this for you. If you want to connect to the internet, the Motorola MR1900 is an AC1900 router.
The reason for a modem's four ports needs to be explained. It's very important to know that the MB8600 doesn't have routing. The MB8600 is just a modem. You can use any of the ports on MB8600 to connect your router. If Comcast's new DOCSIS 3.1 service is used, the link between the router and the modem can then use the full speed of that service. It's expected that Comcast and other cable providers will be able to offer services faster than 1 Gbps in the near future. As soon as faster services are available, the MB8600 will need to have more ports. If you connect the MB8600's ports 1 and 2, you get up to 2 Gbps. The MB8600 has two more ports that can be used for more port bonding at speeds above 2 Gbps. At speeds above 1 Gbps, the router connected to the MB8600 must also do port bonding in order to use the MB8600's port bonding. There aren't any consumer routers that can do port bonding right now. There are a lot of routers used in business networks that can do port bonding. With port bonding in the future, routers for people at home and small businesses will be sold. This will let them take advantage of future service speeds that are faster than 1Gbps. Because the MB8600 has four ports, it can give service speeds of more than 1 Gbps when they're available. That is a great idea. Before you buy a modem that claims to be faster than 1Gbps but doesn't have a lot of ports that can be bonded together, think about it. Without a way to get the fast speed from your modem, you won't be able to get a speed faster than 1 Gbps. A router with bonded GigE ports can get speeds of up to 1 Gbps from the MB8600. Other modems aren't built as well as ours.
A 2.5 GB Ethernet port can connect even the fastest routers and computers to the internet at speeds of up to 800 Mbps downstream and 2,500 Mbps upstream. This is possible if your internet service package allows it. It improves the performance of apps that use the internet, like games, conferencing, and streaming. Active Queue Management helps cut down on Internet latency (AQM). It saves the average family $168 a year to own their own modem, because they don't have to rent one. (Savings depend on which service provider you use.)