Download speed randomly varies from normal (100 Mbps) to very slow (0.5 Mbps); upload is normal

[mkbaddigam]

D/L speed will randomly vary from normal (100 Mbps) to slow (0.5 Mbps) intermittently through the day. Last time this happened was 8 months ago and was fixed by replacing all coax cables and splitters from CABLE-IN to the modem. Replaced again this time with no improvement. Have reset/rebooted all modem/router and tried wired/wifi connection through router and wired direct through modem with no difference in results. Cable man said signal coming into the house is fine. At a loss for what to do.

ISP: Spectrum
Modem: Netgear CM600
Router: TP-Link Archer C5400

Devices: combination of Apple laptops and mobile devices, HP desktop, Xbox, and multiple smart applicances

 

[Someone Somewhere]

Does it happen on all devices, or just one?

Is it slow to everywhere, or just some sites?

 

[mkbaddigam]

Does it happen on all devices, or just one?

Is it slow to everywhere, or just some sites?

It happens to all devices. It is most noticeable on the Xbox as we get booted from game servers if the drop in speed is more than a few seconds. On the other devices, it is only noticeable if the drop lasts longer.

It is slow to all sites. I've tried multiple different speed tests as well, and the speed drop is pretty consistently down to 0.5 Mbps whereas the upload stays in the 10-12 Mbps range.

 

[Groveling_Wyrm]

If you have wired directly through the modem, and gotten no different results, then the problem is not on your end. Just because the signal coming into your home is fine, does not mean your connection is fine. You could be connected to a bad node, or they could be having issues on their end of the issue. I would contact tech support for your Internet Service Provider, and talk very serious talk with them about it.

 

[velocityg4]

Before contacting them. You can try changing DNS servers. Login to you’re router. Change the DNS settings for your internet (WAN) to Google’s.

Primary 8.8.8.8
Secondary 8.8.4.4

 

[mkbaddigam]

Before contacting them. You can try changing DNS servers. Login to you’re router. Change the DNS settings for your internet (WAN) to Google’s.

Primary 8.8.8.8
Secondary 8.8.4.4

The drop in speed occurs even after bypassing the router and plugging directly into the modem, so I don't think changing DNS will have an effect. But I'll try that today through tomorrow and see if any difference is noticeable. Thank you for the suggestion.

 

[mkbaddigam]

If you have wired directly through the modem, and gotten no different results, then the problem is not on your end. Just because the signal coming into your home is fine, does not mean your connection is fine. You could be connected to a bad node, or they could be having issues on their end of the issue. I would contact tech support for your Internet Service Provider, and talk very serious talk with them about it.

Yeah, I think it is something on their end. I'm willing to do a little grunt work myself beforehand though. I figure I'll get a few suggestions from this forum. I'll try those first. If they don't work, I'll at least have some better data for the ISP as to what isn't the problem.