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How To Install a New Cable Modem

So your cable modem went out, you don’t want to take an hour off of work to have a technician come over. How can you replace it? Well you can’t just plug it in like you can with DSL and it work. Also most cable providers don’t have a good ‘set it up yourself’ method as many DSL companies do.

Step 1 – Go get a new cable modem. Most big box electronics places like Best Buy Sell them. Refer to the notes at the end of the post for what the two major ISPs now use before you go shopping.

Step 2 – Remove the old modem. Remember what cables went where.

Step 3 – Unplug the power from your router, or turn your computer off if connected directly.

Step 4 – Plug in the new modem starting with the coaxial cable (this is the big cable with the screw on end. Do not use tools to connect this as you can damage the connector on the modem. Tighten this with your fingers until it is “just tight”.

Step 5 – Plug the ethernet cable in next (the one that looks like a large phone cable). Do NOT plug the power in.

Step 6 – Call your Internet Service provider and get to the tech support option. I’ve included phone numbers below for Comcast and Suddenlink.

Step 7 – Tell the tech support person your account info so they can look you up then tell them that you want to “provision a new modem” and take the old modem off your account.

Step 8 – They will ask for the MAC address of the modem. This is usually labeled clearly on the bottom of the modem. Most manufacturers print this on the box as well. MAC Addresses look like this 00-00-00-00-00-00. They contain numbers and the letters A through F.

Step 9 – They may ask for the serial number too. Motorola serials are something like 24 digits long and has only numbers. Don’t’ confuse this with the Customer Serial which is shorter and has letters.

Step 10 – Follow the instructions the tech support agent gives you. You may need to reboot some stuff a few times.

Step Done – You should have internet!

Modems By Provider

I’d love to add more links here. If someone would send me information for their local cable internet providers. 
I highly recommend the Motorola SB6121 modem. Both Suddenlink and Comcast list it as compatible with their service. It’s easy to find at Best Buy or you can order one here: Motorola Surfboard Cable Modem SB6121
Comcast – Comcast has a modem compatibility tool here:
Suddenlink – You need at least a DOCSIS 3.0 modem to get the best service. The compatibility list here:

Tech Support Numbers

Comcast – 1-800-XFINITY – 1-800-934-6489 is the number in real person digits. This is their main 800 number listed on their website.
Suddenlink – 877-794-2724 is the tech support number listed on their website but may be regional to the southwest. There is also 1-888-822-5151 which might be all purpose.
If you hate working the menus here’s a link to Get Human’s instructions for getting a human:
I do not endorse the Get Human method, but some people might find it useful.

Motorola SB6121 Instructions

Here’s a link to Motorola’s quick start and user guide instructions for the cable modem I recommend. The quick start guide is included in your manual.
Quick Start Guide – This is quick guide to installation.
User Guide – This one has a little more details on how to set it up and what the lights mean.

3 replies on “How To Install a New Cable Modem”

If both of your computers will be using just celbas to connect, you will want to use a switch’. You can use a hub’, both of which allow several network devices to be on the same network, however, switches allow all of the devices to run at their independent speeds (although both computers will have to share the bandwidth of your DSL modem).However, a switch is fairly inexpensive and provided that you buy one with full duplex, both machines will run equally well on the network copying files either to or from the other computer.You can also purchase a wireless switch, such as a NetGear or LinkSys, which works similar, just with or without the celbas.Typically you would connect your DSL modem’s cable into one of the normal switch ports along with your two machines.Hubs and Switches (as well as their wireless counterparts) can be found in the networking accessories aisle of most consumer electronics retail outlets, like Best Buy, Circuit City, CompUSA, or other vendors online.

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