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Randy The Tech Professor

March 6, 2012 at 8:47 pm

Not Getting 50 Mbps Download Speed From Comcast? Here’s How!

Hello everyone,

Note: Part 2 (October 2014) of this post can be found here. Part 3 (June 2015) can be found here.

I have run into this situation twice in the past week:

Both people had signed up for Comcasts XFINITY Extreme 50 High Speed Internet (50 Mbps download speed), but neither were getting the promised speeds. In fact they were only getting about half (24 Mbps) of what they were paying Comcast for. What was going on here? Was it Comcast again?

Actually no! I found out that two essential things were missing from each persons network setup:

1) The Modem: If your Comcast connection rate is 20 Mbps or greater your modem should be a DOCSIS 3.0 Cable Modem. Once again, you must use a DOCSIS 3.0 Modem in order to take full advantage of Comcast’s fast Internet speeds! You can rent one from Comcast or buy your own. I recommend buying your own.

2) The Router: Your router must have both LAN and WAN Gigabit functionality. The WAN Ethernet 10/100/1000 Gigabit ports are for establishing a wired connection to your broadband Ethernet-enabled DOCSIS 3.0 modem. The LAN Gigabit Ethernet ports are for establishing high-speed wired connections to your desktop PC. Once again, connect the router to the cable modem through a Gigabit WAN port, and connect your other PCs, servers, wireless-N access points, or anything else to the LAN Gigabit Ethernet Ports.

Once the DOCSIS 3.0 Modem and the Gigabit Router were hooked up, download speeds of over 50Mbps came flowing in!

Professor Randy says: Don’t buy a router that doesn’t have both LAN and WAN Gigabit ports, and don’t expect extreme Comcast download speeds without a DOCSIS 3.0 Modem!



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  • Sam
    10:25 am on May 22nd, 2015 1

    @Hasan, could you connect to ethernet by chance? I have a similar issue in my home. Every hardline PC gets 120+ MBPS down but my laptop only gets 30 MPPS down but my issue is the laptop’s wireless receiver is not fast enough.

  • Missy
    9:29 pm on June 5th, 2015 2

    Over the past 6 weeks, my Comcast internet (50mbps) has been completely out about half the time. After a tech visit a week ago, I started getting speeds of 2 to 10 over the new Comcast modem with wireless gateway. Today the tech came again and replaced a splitter and an outside wire. I’m getting speeds of over 50 wired and 15-20 wifi. The internet ready TV buffers every 1-2 minutes when I stream Netflix, which is no better than it was before any of the fixes. I rarely ever had trouble streaming before even when I still had the 25 Mbps service. I’m at my wits end with Comcast after spending about 40 hours on the phone with them and waiting a week each time for two tech appts.

  • Missy
    10:12 pm on June 5th, 2015 3

    Additional info for previous post: TV download speed shows as 700 – 900 kb/sec.

  • Randy Knowles
    12:12 am on June 6th, 2015 4

    Hi Missy,

    Thanks for the comment. Possibility #1: Netflix has outgrown its allotted bandwidth, and thus Netflix traffic is now being throttled by Comcast and core network operators.

    Possibility #2: Crummy router. Don’t use the wireless capability of the Comcast modem/router. Put the modem/router into “bridge mode”, and use a dedicated router of your choice. Like this one:

    Also, go into the Netflix settings and uncheck “best video quality”, and set to “auto”. Position the router in a central area.

    Let me know how it goes,

    Randy Knowles

  • Jim Ensley
    11:11 am on August 17th, 2015 5

    I was showing speedtests of 3 to 30mbps. Most times 3 to 4mbps. A tech came out from Suddenlink and showed 50mbps coming from the modem. That’s what I’m paying for.
    A speed test today showed 3mbps. I did a speed test on my laptop from the same router and it’s showing 50mbps. The speed test on my pc shows the same if I go through my router or connect direct to the modem.
    What could be wrong with my computer that the speed is testing so slow? I have an HP that’s about 6 years old and use the Vista os.
    Not very good with computers so any help stated simply would be great!

  • Matthew
    6:09 pm on November 3rd, 2015 6

    I’m sorry but after reading this, and knowing this information already I’ve already purchased a DOCSIS 3.0 Modem (Motorola SURFboard SB6121 172 MBps Cable Modem – DOCSIS 3.0) and I have a pretty decent router (Linksys WRT1900AC Wireless AC Dual Band Router AC1900) I’m also using my ASUS PCE-AC68 Dual-band Wireless-AC1900 Adapter IEEE 802.11ac, IEEE 802.11a/b/g/n PCI Express adapter and still received about 27mb/s download rates. Please explain what and where I’m going wrong to “take full advantage” of the “50mb/s” I’m suppossedly suppossed to be getting.

  • bnrandpon m
    2:09 am on February 17th, 2016 7

    I have a wndr3700 v.3 is that a router for good enternet speed


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