dslreports logo
    All Forums Hot Topics Gallery


how-to block ads

Search Topic:
share rss forum feed



[FL] Speed degrades over time / Reboots required

Having issues with my cable internet out of Crestview, FL. Was good for almost 4 years, enjoying Preferred speeds between 10-20Mbit. Noticed one day that my internet could no longer stream 720P video, which it could normally tear through. Then noticed that my Cox Internet Speed Check and Speedtest speeds would fall between 2-5Mbit, well below Preferred speeds. Since then, I've been without wireless router, with two different ones I own (Linksys WRT54GL and E2000), tried two different modems (Motorola SB5100 and Linksys CM100), and the problem still occurs. It gets slow, I reboot the modem or the Cox tech sends a signal to reboot it, it temporarily restores speed between 1-6 hours then degrades again and does not come back until I reset again. The attached picture shows my slow speeds, and shows fast speeds again after a reboot of my modem via me power cycling the modem, resetting from within the config, or a re-provision from a chat/phone tech.

I've had two Cox technicians come to the house now, and I'm on the chat and phone with Cox service nightly to make logs to my account with the issue. First technician replaced the splitter outside the house (took it from 4 way to a 3 way), and tried to give me a signal dampener to reduce the power level of the downstream from +9db to +4db. I've taken it off since then because a.) it didn't help and b.) the second technician said the power level was fine with just replacing the 4 way to a 3 way (took it from +9 to +7).

The first technician also replaced the ends of the cables at the green box in the yard that splits the cable between me and my neighbor, and at the gray box attached to my house, and then gave me a new cable for the room the cable modem is in. The second technician did absolutely nothing but look at my power level and signals and then left. He recommended a DOCSIS 3.0 modem, although the first technician said it wasn't needed due to only being on Preferred speeds. I've asked chat/phone + the first tech if I am competing for bandwidth on the single channel and if that's causing degradation of the signal over time and they insist that can't be it. It doesn't sound like it would be the issue either. This came out of nowhere one day after 4 solid years of use, and it hasn't been good since.

Frequency 831000000 Hz Locked
Signal to Noise Ratio 39 dB
Power Level 7 dBmV
The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
Upstream Value
Channel ID 3
Frequency 24512000 Hz Ranged
Power Level 44 dBmV

That's a snapshot from my SB5100 right now, which is currently my active modem. I could always switch back to the CM100, but it wouldn't fix anything. Two technicians (contracted out from Comcast no less? That's horrible Cox!!!) and 14 days of chatting with tech support. I'm desperate for help...both myself and my gf work on ethernet networks for DoD on a daily basis, and I along with the Cox techs that have been out can assure you that the cause of this issue is not inside the house. Had this issue in Yorktown as a customer. Took a month of calling and a talk with the district manager to finally get an engineer to fix an issue with the junction box for the entire neighborhood. I don't want to go through that here, but I will if I must. I'm hoping I'm just missing something here that maybe the technician missed, or that someone else can confirm this issue with either slow speeds in NW FL or that not being on DOC3 is causing this issue.


Portsmouth, VA
Your problem is.... You're using a very old modem, which need's to be replaced with a newer D3 modem like Cisco DPC3010, or Motorola SB6141. Your current modem can only lock onto one downstream, and one upstream channel. That one downstream channel is only capable of around 38mbps max, and that's shared with other's in your area. With one of the two listed modem's above, both can bond up to 8 downstream channel's, and up to 4 upstream channel's. Meaning if cox in your area has 8 downstream channel's available, you have 8x38mbps of bandwidth available to you. Meaning a lot less chances for speed slowdown's.

As for the possible reason speed's get faster after a reboot, the modem could be locking onto a less crowded downstream channel. Which end's up getting crowded over time, and causes speed's to get slow again. Also the router's you are using are rather old, and probably should be upgraded as well. So pretty much what I am suggesting is, it is time to upgrade your rather old equipment(Modem/Router).


Niceville, FL
reply to XenoCrescens
Being in Niceville, a few months ago I started noticing something similar with my old Scientific American Modem, it was DOCSIS 2.0. I went to the local office, bought the DOCSIS 3.0 modem and installed it myself. Since then I have not had a problem and have consistent speeds. The multiple channels available in the DOCSIS 3.0 modems allow for a much more stable connection as it can swap channels or push more data through the less problematic channels providing a much better and stable connection speed.

Another major thing that can greatly impact speed reported:
Computer speed - run full system virus scans and CCleaner, also faster computers consistently get faster speeds as long as it is clean and running well. On my Athlon 3500+ older system that runs well but is 8-9 years old, I see speed vary all the time from 5Mb to 16Mb... versus my newer Intel Core2 system, I see consistent 18-24Mb speeds and lower pings.
Also keep an eye on the router logs to see if someone else in the neighborhood may be leeching off your wifi.