Ask Daley: cable modems and routers

Welcome to the second installment of Ask Daley! Today’s question comes from Joshua:

I need a modem and a wireless router for a new installation at my home.

The MMM forums where you make your recommendation for this device is currently down, so I found your personal site.
For a new installation, would it be most cost effective to get the “Qwest Actiontec PK5000 DSL Modem 4 Port Wireless Router” all in one device on your recommendations page?

Is there any reason not to get it all in one device?

I plan to be using Comcast Xfinity service here in South Florida.


Thanks for writing, Joshua! Let’s jump right into your question.

First, I’d like to apologize for the “recommendation” of the Qwest Actiontec PK5000 DSL Modem in the Shopping Hut. I’m actually in the middle of a major overhaul of the storefront, and the page that you saw that item was not a page tailored with custom recommendations from myself, but just a generic category listing from Amazon. I will try and correct that as soon as time allows me.

Now, if you’re planning to utilize Comcast for your internet connection, you will not be able to use a DSL modem. DSL equipment is for, well, DSL broadband use through the old copper phone lines via AT&T, Verizon, etc., and not through coaxial cable. Cable ISPs utilize a modem with a coax connector that uses the DOCSIS (Data Over Cable Service Interface Specification) specification. As such, you’d needĀ a DOCSIS complaint cable modem.

As for all-in-one devices versus individual parts, I typically recommend buying individual parts as you eliminate the added cost and downtime if one of the integrated components were to fail, and you’re provided an added layer of security and control over your networking, as well as the option to easier upgrade individual components if necessary. This approach creates a slightly messier communications hub due to the added wiring and uses a smidgen more electricity, but it’s a reasonable trade-off in my humble opinion.

As for specific models of modem to use, it’s always best to check and ensure that whatever modem you’re looking to buy is on your ISP’s approved hardware list. In the case of Comcast/Xfinity, the website with that list of devices is here:

You will note that they require DOCSIS 3.0 modems for all service levels but Economy Plus and Performance Starter, which can still utilize DOCSIS 2.0 modems. If you’re familiar with the superguide on the MMM forums, you’ll probably already know that most people can get by comfortably on 3Mbps or so download speeds, so going with the slower speed packages could save you more money on a multitude of fronts unless Comcast decides to force everyone over to DOCSIS 3.0 in the future, a possibility that might be worth considering and easy enough to hedge against.

As for brands of cable modem, you can never go wrong with a Motorola Surfboard. I run a SB5101U myself with Cox, and it’s run like a champ for nearly three years now and only cost me $50. The SB5101U (DOCSIS 2.0), SB6121 (DOCSIS 3.0), and SBG6580 (DOCSIS 3.0 w/integrated router) are all on their approved devices list (note, the following links are referral links for Amazon):

Motorola SB5101U DOCSIS 2.0 modem (~$50)
Motorola SB6121 DOCSIS 3.0 modem (~$80)
Motorola SBG6580 DOCSIS 3.0 modem with integrated wireless router (~$125)

Now, if you do choose to go with the separate router, some of the best going for the money currently are from Asus, with the RT-N12 and the RT-N13U if you want USB support being good bang-for-buck models as they both have decent default firmware and options so long as you update the firmware, and also supports DD-WRT if desired.

Alternately, if you want to go with a model with DD-WRT pre-loaded, there’s also the selection of routers from Buffalo, including the WHR-300HP or WZR-300HP if you want USB support. All told, these are all devices with about the same build quality (again note, the following links are referral links for Amazon):

Asus RT-N12/B wireless router (~$40)
Asus RT-N13U/B wireless router with USB port (~$60)
Buffalo WHR-300HP wireless router (~$50)
Buffalo WZR-300HP wireless router with USB port (~$60)

As you can tell by the prices, there’s really not much financial advantage to buying the Motorola SBG6580 with the wireless router integrated.

Finally, let’s talk uninterruptible power supplies, or as they’re better known as, UPS devices. You don’t necessarily have to get one, but it’s not a bad idea to put your networking equipment on regulated power to help extend it’s lifespan and help keep it operational during shorter outages if you happen to utilize VoIP telephony at your home. It’s frequently been useful in the past being able to have an operational internet connection after an outage in our neck of the woods as they’re usually coupled with storms, and we can still call, check radar maps, and assure loved ones that we’re still alive. Of course, your mileage and usefulness may vary.

The advantages of running a UPS to keep things simple is that it protects against both surges and brownouts, and allows you to run the equipment for an amount of time after an outage. In my meatspace line of work, I always recommend my clients run their computers off of a UPS to help maximize the longevity of their equipment and protect against electrical damage, which hard drives are especially vulnerable to. The great thing is, if you have a desktop, you can frequently just buy a beefier UPS model and just put your desktop and the networking equipment all on the same unit so you don’t have to have a separate supply for the network gear. The only secret there is to ensure your desktop shuts down rapidly after a power interruption to maximize battery life for the network.

The thing to look for in a good UPS is auto voltage regulation, or AVR… and if you’re not afraid to spend a few hundred on one, it’s also not a bad idea to buy a model that does true sine wave output, but that’s a subject for another time. On the lower end of the spectrum, CyberPower makes good models with replaceable lead-acid batteries and are good units for people not wanting to break the bank with their UPS investment. On the higher end is APC, the gold standard of UPS manufacturers and the brand most used in enterprise deployments and datacenters. A UPS for any mid-range desktop from the past five years coupled with your networking equipment, I’d target a volt-amp rating of around 1000-1500VA with a wattage of at least 600W. Here’s a couple good modelsĀ (again, the following links are referral links for Amazon):

CyberPower CP1200AVR UPS (~$125)
CyberPower CP1350PFCLCD true sine wave UPS (~$170)
APC BR1000G Back-UPS Pro UPS (~$130)
APC SMC1000 Smart-UPS true sine wave UPS (~$265)

Personally, I use the CP1200AVR units in my own house and for my equipment. They’re not top of the line, but they’ve served well over the years. Again, these aren’t things that you have to get… but if you’re running a desktop computer anyway, it’s not like a good UPS isn’t worth the investment to help protect that investment, and you get the added bonus of being able to run the network equipment off it as well. If you just want to invest in a UPS for just the network equipment, then clearly you won’t need quite as beefy a unit. However, keep in mind, the higher the VA rating, the longer the battery will last in a power outage.

Anyway, that should get you set up! As for the other readers, feel free to crib off of this if you’re in a similar situation with needing equipment for a cable internet provider, it’s pretty universal stuff.

If you’ve found this information useful, please consider utilizing the referral links in this article or consider giving to Technical Meshugana directly by using the donation link at the top right of the page. We don’t sell advertisements, so your generosity will help keep this resource available. Thank you!

8 thoughts on “Ask Daley: cable modems and routers

  1. Daley, I know you’re not tech support, but I trust you more than the bozos on the Comcast tech support line.

    I went with the Motorola SB6121 DOCSIS 3.0 modem and Buffalo WZR-300HP wireless router with USB port and hooked them up with Comcast Xfinity service.

    The modem worked fine and seems to work fine as long as I don’t start the wireless router. When I start the wireless router, it causes the modem to continually reset itself.

    When it began, it was about every 6 minutes. Now it’s about every 2 minutes.

    So far, I’ve mainly tried resetting the router and modem in the sequence suggested by tech support. My next call is to Buffalo tech support to see if they have ideas.

    Do those symptoms smell like anything to you?

    • I don’t mind, Joshua… tech support’s technically been my bread and butter for over a decade!

      I do know some cable companies dislike you bringing your own router to the party. Myself, I have to clone/spoof a MAC address from one of my desktop computers with my router in order to get the two to play nice together, and I’ve known others who have done the same on Cox, Comcast, Suddenlink, TWC and Charter… and the support monkeys never tell you this. Under the DD-WRT interface (as that should be what’s installed by Buffalo for your model router), the setting should be under Setup > MAC Address Clone. The easiest option is to just clone your NIC’s MAC address from the system that can successfully connect to the cable modem and get a connection.

      Start by disconnecting the ethernet cable going from the router to the cable modem until after you have cloned the MAC address and configured it manually. Also, stay away from Buffalo’s configuration tools on their CD and just stick with the manual. Once you’ve cloned over a good MAC address, you just need to set and save the basics on the Setup > Basic Setup tab. For Comcast (IIRC from my experience with them in the past), the most important settings are:

      Connection Type: DHCP
      STP: Disable

      Once the proper configuration settings are saved and before reconnecting the router to the modem, unplug the modem for about a minute and then plug the modem back in. Once the modem gets a signal and goes stable, unplug the router’s power and connect the ethernet cable between it and the modem, then plug the power back in on the router. Knock wood, you should be stable and it should just work from that point forward.

      • Daley,

        How do you figure out what Mac address to put into the system? I tried this and used one of the “one-click options” under the “Clone Mac address” system, and it seemed to make it more stable for a bit, but now it’s as cranky as ever. I’d like to try a different Mac address, but I don’t understand where to get the numbers…is it something I read in the manual or somewhere else?

        Sorry, this is my first time putting this together…

        • Typically, the best source for MAC address numbers is from a desktop or laptop computer that you can get to connect successfully to the cable modem without problem. Beyond that, you can use an online MAC address generator, or just make your own up so long as you remember that the valid characters are 0-9 and a-f (hexidecimal), and you ensure that the first byte of the address (xx:00:00:00:00:00) is even (00, 02, 04, etc. – a good breakdown on MAC address basics can be had here). Personal favorites involve variants on using words: BE:EF, BA:BE, CA:FE, and DE:AD are all popular spoof address segments. You could always try something like 00:CA:FE:BE:EF:22 as an example, which should work.

          All that said and the minor crash course on MAC addresses aside, if a MAC address change got it working but you’ve gone unstable since, there might be problems on the ISP end. Most Motorola Surfboard modems have a configuration and diagnostics interface accessible at, you might want to check the logs and signal strength to see if other things might be afoot, because once you get the modem and router talking for a connection, it should just work. If it doesn’t, start looking at other causes like defective new hardware (it happens even with the good stuff – you’ll get a turkey out of the box), or more common with new installs, undiagnosed line noise issues.

  2. Daley,

    This is super, super helpful. Thank you for the advice. I really appreciate your answering my question!

Leave a Comment