Question Having serious issues with download speeds

jamesdsimone · May 14, 2025

So recently my download speeds have been in the tank. I started about a week or 10 days ago. I'm getting 10% of my usual download speeds. My internet connection is ok but it makes loading complex pages slow and downloading anything nearly impossible. I even noticed when updating Mint the download speeds are 200-300 Kps when usually they are 2-3 Mps.I have tried multiple machines with Windows 7, Windows 10 and Linux Mint. All the connections are wired. I have rebooted the router and modem multiple times and had Cox reset the connection. Any ideas what to do next? Are there any router settings that might have somehow gotten changed?

In2Photos · May 14, 2025

Have you tried connecting a PC directly to the modem? Did you use a different cable for each PC or the same one? Have you replaced the cable from the modem to the router? Does the router have a built-in speed test? Check to see if QOS is enabled in the router. If it is disable it and test again.

jamesdsimone · May 15, 2025

In2Photos said:
Have you tried connecting a PC directly to the modem? Did you use a different cable for each PC or the same one? Have you replaced the cable from the modem to the router? Does the router have a built-in speed test? Check to see if QOS is enabled in the router. If it is disable it and test again.

Yes tried that and got the same slow rates so can rule out the router. I tried several online speed tests and they all give less than 20mbs. I'm theoretically supposed be getting 500mbs. What modem settings should I look at? Also not sure if this helps but the download speeds seem to be proportional so a site I usually get 5-6mbs I'm getting 500-600kbs and 500kbs goes to 50kps

mindless1 · May 15, 2025

If you can access the modem ~~settings~~ pages, look at the signal strength and logs to see if it's maintaining a good connection. Normally there aren't any other settings to change on a modem, all pushed to it by the ISP.

jamesdsimone · May 15, 2025

mindless1 said:
If you can access the modem ~~settings~~ pages, look at the signal strength and logs to see if it's maintaining a good connection. Normally there aren't any other settings to change on a modem, all pushed to it by the ISP.

I'll check it when I get home. I have had the connection reset and rebooted the modem 2 or 3 times.

iamgenius · May 15, 2025

Maybe the issue is from your ISP side? Ask them to check the connection health.

JackMDS · May 15, 2025

Disconnect everything (include disable wireless) from the Modem/Router, connect via short CAT6 wire one good computer, and check the speed (https://www.speedtest.net).

If the speed is Ok, then the problem is in your Network. If so connect back one computer at the time to find what causing it.

If it is low with one wired computer attached, then the issue is the Router, or Modem or ISP.

Unfortunately providing only the name of the OS that run on your computers it not really relevant too much to solve the problem It can be the ISP service and ot any other Network issue and there is No info in any of it in your posting.

jamesdsimone · May 15, 2025

iamgenius said:
Maybe the issue is from your ISP side? Ask them to check the connection health.

I have contacted them. I want to rule out a problem on my end before getting a service call.

jamesdsimone · May 15, 2025

JackMDS said:
Disconnect everything (include disable wireless) from the Modem/Router, connect via short CAT6 wire one good computer, and check the speed (https://www.speedtest.net).

If the speed is Ok, then the problem is in your Network. If so connect back one computer at the time to find what causing it.

If it is low with one wired computer attached, then the issue is the Router, or Modem or ISP.

Unfortunately providing only the name of the OS that run on your computers it not really relevant too much to solve the problem It can be the ISP service and ot any other Network issue and there is No info in any of it in your posting.

I tried multiple computers/OS's to rule out it being a problem with a specific computer. I've have tried connecting directly to the modem bypassing the router and got the same result. I used a computer running Mint 22.1 with everything updated so it isn't an outdated driver or browser issue. I'm thinking ISP issue at this point.

JackMDS · May 15, 2025

Well, one thing left. Call your ISP and tell them what is the output of the Modem.

mindless1 · May 15, 2025

JackMDS said:
... check the speed (https://www.speedtest.net).

Speedtest.net has been spotty/offline a lot in the past ~3 days. Couldn't connect to the site at all a couple hours ago (so used fast.com instead), but now can again.

jamesdsimone · May 15, 2025

JackMDS said:
Well, one thing left. Call your ISP and tell them what is the output of the Modem.

I scheduled a service call.

jamesdsimone · May 18, 2025

Turns out their equipment on the pole was failing. It was giving multiple errors. I assume it has some error correction that was throttling down the speed.

DaaQ · May 18, 2025

Are you using purchased equipment or ISP provided one? Is the modem DOCSIS 3.0 or 3.1? On a 3.0 with 16 bonded channels, 500 is about the max it can do. If 3.1 then you "should have about a 10-20% overhead" depending on the particular ISP. You really want to be on D3.1 it has more robust forward error correction built in.

jamesdsimone · May 18, 2025

DaaQ said:
Are you using purchased equipment or ISP provided one? Is the modem DOCSIS 3.0 or 3.1? On a 3.0 with 16 bonded channels, 500 is about the max it can do. If 3.1 then you "should have about a 10-20% overhead" depending on the particular ISP. You really want to be on D3.1 it has more robust forward error correction built in.

The equipment is mine. The problem was with their equipment outside. It is fixed. My speed went from less than 20Mbs to almost 600Mbs.

DaaQ · May 18, 2025

jamesdsimone said:
The equipment is mine. The problem was with their equipment outside. It is fixed. My speed went from less than 20Mbs to almost 600Mbs.

Don't take this the wrong way, but ISPs will upgrade their carrier/modulation schemes, and it can have an effect on how purchased equipment performs.

On the flip side regardless of it is purchased or leased, I have seen modems cause whole port degradation because it starts pushing noise back into the system only when it registers on the network and starts passing data . I call it modem burst noise. It has a specific waveform to it.

Not saying this is your situation at all. But if you are on a Node+x then it could be caused from a node on the other side of the county.

This is only point I am trying to get across.

I seen someone above mention high split HFC. That could potentially get you to full duplex. Where I am, we are still low split, and max upload capacity is about 175M. Plans are still 1G down and 50M up. with the 20% additional provisioning. So top speeds would reach 1.2G and 68ish up. Obviously the 1.2 down would depend on customer's equipment. where they will probably max at 975ish with the overhead.

Other point is if you are on a D3.0 modem, make it a priority to change to a D3.1 asap. D4.0 is also coming.

jamesdsimone · May 18, 2025

There is only me on the network so 600Mbs is more than adequate. I don't plan on upgrading anytime soon.

mindless1 · May 19, 2025

I was resistant to update my self owned D3.0 modem, then one day the ISP notified me that I got a "free" speed upgrade, yet soon I wasn't even getting the same speed I used to before the upgrade.

They wanted to give me a rental-free D3.1 modem, wouldn't even troubleshoot the performance issue without my taking it, so I did.

That solved the problem, except that a few months later, the transition to high split was complete and I was notified of a symmetrical upload speed upgrade. I'm only getting that u/l speed once in a blue moon, normally closer to 100Mb. It's not the network adapter or cable, getting full d/l speeds and full lan file transfer speeds.

Had an ISP tech on site for another reason and he looked at it while there, concluded everything was fine on my end, didn't even want to swap the modem, apparently just ISP network congestion or in it's current state, at-capacity.

DaaQ · May 19, 2025

mindless1 said:
I was resistant to update my self owned D3.0 modem, then one day the ISP notified me that I got a "free" speed upgrade, yet soon I wasn't even getting the same speed I used to before the upgrade.

They wanted to give me a rental-free D3.1 modem, wouldn't even troubleshoot the performance issue without my taking it, so I did.

That solved the problem, except that a few months later, the transition to high split was complete and I was notified of a symmetrical upload speed upgrade. I'm only getting that u/l speed once in a blue moon, normally closer to 100Mb. It's not the network adapter or cable, getting full d/l speeds and full lan file transfer speeds.

Had an ISP tech on site for another reason and he looked at it while there, concluded everything was fine on my end, didn't even want to swap the modem, apparently just ISP network congestion or in it's current state, at-capacity.

Depending on how that ISP has it's stuff setup, if it is Node+0 then there are probably over 200 subscribers on it. If they are Node+x then port congestion starts happening, I have a heavily loaded port that all they need to do is split 2 nodes from that port to a low volume port. In the evening it's upstream capacity is going over 100%. probably around 115 to 120 from what i can see on the graphs.

I have pointed this out to "supervision" even sent the screens of 2 of the 4 nodes going over 100% everyday starting around 8pm tapers off around 11pm-1am. But I have BAD supervisor. So it will take the customers complaining to corporate.

Worst of it is, we are low split. Lucky if we can get to 42 MHz because the line gear has alot of 40 MHz return EQs in them. On top of that the geniuses decided to put the ETDMA channel at 36 MHz and start the OFDMA at 9.8 MHz - 42 MHz. OFDMA if you are familiar scans left to right on the subcarriers. The majority of system noise is generally under the first 15 MHz or so. So instead of putting the 6MHZ QAM alignment channel down there they put it up at 36.8 MHz. Just total face palms over here.

Falling off my soapbox now.

Question Having serious issues with download speeds

jamesdsimone

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In2Photos

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jamesdsimone

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mindless1

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jamesdsimone

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iamgenius

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JackMDS

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mindless1

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DaaQ

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