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Thread: Comcast issues, replacing modem made things worse

  1. #1
    Junior Member
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    Jan 2017
    Georgia, USA

    Comcast issues, replacing modem made things worse

    Good evening. I've been a Comcast customer for years now and several months ago I began to have a problem with random loss of connection throughout the day, usually to the tune of at least 8 to 10 incidents per day. is a screenshot of the modem's logs from about a month ago showing the sorts of things that usually popped up during these incidents. The power loss incidents were all my doing (power cycles once the dropping began on a given day in a vain attempt to see if that would help stabilize things).

    Several people told me that this was likely an issue with the "box outside", whatever that means, but Comcast really dug their heels in whenever I brought this up so I decided to eliminate the other elephants in the room. Namely, my older model modem and even older router.

    Fast-forward to today. Replaced the modem with a Netgear CM1000 and the router with a DLink DIR-880L. I didn't expect them to make a difference but I was only getting ~60Mbps downstream on a 150+ connection package even during the good times so I wanted to take care of two problems at once.

    Somehow, the upgrade made things much, much worse.

    Before the equipment upgrade:
    After the equipment upgrade:

    While the connection is technically functional, I noticed that it is taking awhile to load webpages. Not that the data is being transmited slowly but that inputting a URL will usually result in the browser sitting there with the loading icon showing while it does nothing for ~30-60 seconds before it finally loads the webpage fairly quickly.

    I have no idea what is going on. I used self-provisioning to add the new modem to my Comcast account but I did call them after noticing this huge loss of speed and their people can't figure it out on their end after multiple resets and whatever totems they invoke as part of this process. A technician is supposed to come out on Wednesday to look around and I am hoping to arm myself with more information before he arrives and attempts to outright dismiss the problem like their phone people are so keen to do.

    One thing I did consider: this new modem is DOCSIS 3.1, while the former modem was 3.0. I was told that this would not have a positive difference unless our connection supported it but neither would it have an adverse effect -- that worst-case scenario I would be right back where I started before purchasing the new equipment.

    Is this true? Could the 3.1 modem be having some sort of effect? If not, any of you more knowledgeable folks have a list of things I can check or read up on before Wednesday so that I can get this problem taken care of once and for all? I have no idea how to look at the diagnostics on this new modem and the manual doesn't provide that information so I can't view any info there to post for you here.

    As a note, this issue persists even if I connect the modem directly to the desktop computer and bench the router. Doesn't get any worse when I add the router but nor does it improve the situation. The connection is wired and the network adapter is whatever the integrated one with my mainboard is (board is a Sabertooth z97 Mark 2, adapter is reported as "Intel(R) Ethernet Connection (2) I218-V" in device manager), Windows 10 Pro is the OS.

  2. #2
    Administrator Philip's Avatar
    Join Date
    May 1999
    Jacksonville, Florida, United States
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    Different modems have different sensitivity to line issues, the new one could simply be less tolerant to bad signal levels. You should definitely complain and get them to fix it, having a technician over is a good thing.

    The two sensible things you can do on your end are:

    1. Check the modem signal levels from its stats page. All current cable modems have a web page that you can look at and see whether the signal is within acceptable ranges, as described here:

    2. You can do a couple of traceroutes to see if there is packet loss or latency issues, and how far from your modem they occur.

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