Speed dropout

liderbug · Post by **liderbug** » Tue Nov 17, 2020 10:04 am

Centurylink DSL, 20meg, Technicolor C2100T, Fedora

So every once in a while I click on a link and nothing happens for several seconds or streaming a video, buffering, and it got annoying. So I set up a testing script using speedtest-cli, MariaDB, and Phplot. I run speedtest-cli every 5 minutes and I'm surprised. On a regular basis, every 90 to 100 minutes my speed drops from 19Mb to less than 10Mb. And sometimes it drops to less than 1Mb. IE .2Mb and stays there. Centrurylink says I have too many DHCP reservations and to remove them :-\ or they want me to disconnect every device, turn off WiFi and run a speed test - Hey look it's 20Mb, there's no problem.

I don't have anything internal that runs on the schedule I'm seeing

Suggestions? Thoughts as to the cause. Thanks for any advice.

Each tic mark is 5 minutes. Red is download, green is upload

Post by **Philip** » Wed Nov 18, 2020 7:04 pm

It is possible that there is some periodic interference causing the DSL line to lose sync, or the modem to sync at a lower speed for a bit. I would look into the modem stats page, and see what signal levels you see. There is some basic reference about DSL signal levels here:
https://www.speedguide.net/faq/how-to-f ... d-sync-372

I hope this helps

liderbug · Post by **liderbug** » Tue Dec 29, 2020 10:31 pm

It just went from bad to worse - turns out my wife's desktop was running Carbonite 24x7 and for some reason it seems to be doing save & restore all the time. She set it to "only run between 10pm to 6am. So from 6a to10p my graph is pretty much sitting at 19meg -

Post by **Philip** » Wed Dec 30, 2020 9:46 am

Glad to hear you figured it out! Cloud backups seem to be an often overlooked bandwidth guzzlers I suppose. You can always tweak it by reducing the amount of data being backed, and limiting it's bandwidth too.

Thanks for sharing.

obradka · Post by **obradka** » Sat Jan 02, 2021 3:15 am

Philip wrote:Glad to hear you figured it out! Cloud backups seem to be an often overlooked bandwidth guzzlers I suppose. You can always tweak it by reducing the amount of data being backed, and limiting it's bandwidth too.

Thanks for sharing.

There may be a problem with the integrity of the cable connection. Sometimes I lost speed when running some programs. It is also possible that the speed is lost when updating background applications.