Which Ethernet Cable Should You Use With a Modem?

On this page (7 sections)

1. What Ethernet cable should you use with a modem?
2. How should you choose an ethernet cable for a modem?
3. Which cable length fits your setup?
4. Is Cat 5e enough, or should you choose Cat 6 or Cat 8?
5. Should the modem connect to a router or computer?
6. What mistakes should you avoid when setting up Ethernet?
7. Which ethernet cable for a modem should you choose?

For most homes, a Cat 6 Ethernet cable with RJ45 plugs is a practical ethernet cable for modem-to-router or modem-to-computer connections. Match its length to the route and check the Ethernet ports on both devices before you buy.

The cable carries the wired connection, but it doesn't set your full internet speed. The modem, router or computer, Ethernet ports, and internet plan also affect what speed you can get.

What Ethernet cable should you use with a modem?

Use a Cat 6 cable with RJ45 connectors for a typical home modem connection. All three picks below are Cat 6 cables with RJ45 plugs, with lengths and shapes suited to different routes.

Connect the modem's Ethernet port to a router's WAN or Internet port, or directly to a computer's Ethernet port. A cable modem connects to the wall through a separate coaxial cable, not Ethernet.

If you're choosing equipment too, start with our cable modem buying guide. For the physical setup, see how to connect a modem to a router.

Does Ethernet cable category affect modem speed?

A higher cable category won't make your connection faster than the slowest device or plan in the path. The Jadaol and Amazon Basics cables support up to 10 Gbps and 250 MHz, while the Ultra Clarity Cables cable states up to 10 Gbps and 500 MHz.

Those cable ratings describe their stated capabilities, not the speed your home will receive. Check the Ethernet port speeds on the modem and router, then compare them with your plan.

For context on modem technology and plan limits, read what a cable modem is and how it works.

How should you choose an ethernet cable for a modem?

Choose by connector, route length, and cable shape first. These practical details matter more than a higher speed number if the cable won't fit or reach.

Confirm that both devices have RJ45 Ethernet ports. Measure the path around furniture and along walls, then add enough slack to connect the plugs without pulling the cable taut.

Pick the shortest cable that reaches comfortably. A 10 ft cord suits devices close together, a 50 ft option gives you more room to route around a space, and a 100 ft cable can serve a longer path.

A round cable is a familiar choice for open runs, while a flat cable may follow edges and corners more easily. The flat Jadaol cable includes clips; plan where to attach them before you start routing.

Which cable length fits your setup?

Choose a cable that reaches along your planned route without leaving a large, loose coil. Measure the actual path, including corners and slack at both ends, instead of guessing from the distance between devices.

Is a 10 ft cable enough for a modem and router?

A 10 ft cable is a good fit when the modem and router sit on the same desk, shelf, or nearby section of wall. The Amazon Basics option is a round, black Cat 6 patch cable with snagless plugs.

Choose this short cable when you want little extra cord to manage. Skip it if the route crosses a room or turns around furniture, since a tight cable can pull at the ports.

When does a 50 ft flat cable make sense?

A 50 ft flat cable suits an indoor run that needs to follow walls, edges, or corners. The Jadaol cable includes clips, which can help keep its path organized.

Pick it if the route needs more reach than a short patch cable and a flat profile works for your space. Skip it when the modem and router are close together or when you need a round cable for your setup.

Plan the route before attaching clips. Keep the cable away from sharp bends, door hinges, and places where furniture can crush it, and don't put it under carpet where people walk or furniture presses on it.

Should you buy a 100 ft cable?

A 100 ft cable helps when a measured route between devices is long. The Ultra Clarity Cables option is a round Cat 6 cable with RJ45 connectors and is described for indoor and outdoor use.

Choose it when the extra reach serves a real path, such as a route between rooms. Skip it for a short connection where the spare length would be hard to organize.

Secure the run so it won't snag, pinch, or become a trip hazard. A longer cable can help place a router elsewhere in the home, but it doesn't improve the router's Wi-Fi coverage by itself.

Is Cat 5e enough, or should you choose Cat 6 or Cat 8?

Cat 5e or Cat 6 is usually suitable for home Ethernet, and Cat 8 is rarely needed for a basic modem-to-router link. If you already have a working Cat 5e cable of the right length, you may not need to replace it for a typical home plan.

Cat 6 is a sensible choice when buying a new cable because it supports common Gigabit Ethernet use and has room for faster links when the connected equipment supports them. Paying for a higher category won't raise the speed of a slower port or internet plan.

Should the modem connect to a router or computer?

Connect the modem to a router when you want to share internet with several home devices. A direct modem-to-computer connection can suit one wired computer when your modem and service support it.

For a router setup, connect one end of the cable to the modem's Ethernet port and the other to the router's WAN or Internet port. Then connect other devices to the router over Wi-Fi or Ethernet.

Follow your provider's setup instructions if you switch between a router and a computer. If the connection fails, check that both cable ends are seated and look at the device port lights; our guide to a modem that won't connect to the internet covers other common checks.

What mistakes should you avoid when setting up Ethernet?

Avoid choosing by speed rating alone, guessing the cable length, or connecting to the wrong port. A simple route and port check prevents many setup problems.

• Connect the modem's Ethernet port to the router's WAN or Internet port, not to a LAN port.
• Measure the route around walls and furniture, with a little slack at each end.
• Don't bend, crush, or pinch the cable under a door or heavy furniture.
• Keep Ethernet separate from the coaxial connection between the cable modem and wall outlet.
• Don't expect a new cable to fix provider compatibility, a slow plan, or a modem problem.

If you're shopping for a modem as well, compare modem options for gigabit internet and confirm provider compatibility before changing equipment.

Which ethernet cable for a modem should you choose?

Choose the Amazon Basics Cat 6 cable, 10 ft for devices close together and a tidy short run. Pick the Jadaol Cat 6 cable, 50 ft when you need more reach along indoor walls or corners and want a flat cable with clips.

Choose the Ultra Clarity Cables Cat 6 cable, 100 ft for a long measured route. Whichever ethernet cable for modem setup you choose, confirm both RJ45 ports, leave safe slack, and protect the run from pinches and foot traffic.

Frequently asked questions

What Ethernet cable should I use with a modem?

A Cat 6 cable with RJ45 connectors works for most modem-to-router or modem-to-computer connections. Choose a length that reaches without pulling tight or leaving a large coil, and confirm that both devices have matching Ethernet ports.

Your plan and device ports set the practical speed limit.

Does a modem need Cat 6 or Cat 8?

Most home modem connections don't need Cat 8; Cat 6 is a sensible choice for ordinary Ethernet runs. A cable's category doesn't increase the speed your modem, router, computer, or internet plan can deliver.

Check the device port speeds before paying more for a higher category.

Can I use any Ethernet cable with a modem?

Use an Ethernet cable with RJ45 connectors that fits the modem and the device at the other end. Cat 5e or Cat 6 is usually suitable for a home connection, but check your equipment's ports and the cable length.

Ethernet won't replace the coaxial cable that connects a cable modem to the wall.

How long can an Ethernet cable be from a modem?

A 100 ft Cat 6 cable is available for a longer home run, but the useful choice depends on the route and your equipment. Measure along the path, including turns and slack at each end.

Keep the cable away from places where it could be pinched, pulled, or tripped over.