Intermittent Internet Speeds - Optimum/Cablevision

Hello All,

I have this problem with my internet speeds; when I run Speedtest it quickly shoots up to about 110 Mbps down, and quickly begins to gradually fall, usually ending in the 20's Mbps down.

I started with their modem, switched to a Netgear, then to an Arris. I also started with their Sagecom router, then swapped it for another of their Sagecoms, then bought my own TP-Link. So I've had 3 modems and 3 routers, but this problem is consistent through all.

I've had 3 technicians here; first swapped the router and put new connections on the coax, second replaced something outside the house and ran a bunch of tests, third ran a new cable from the pole to my house, and also scheduled for them to check the "tap" on the pole at the street.

I'm at a total loss, so figured I'd see if anyone has maybe experienced this and has a suggestion. Oh, and my internet plan is for 100Mbps down.

Any insight is greatly appreciated!

Thank you in advance Happy

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doesn't sound like internet speed problem.

That's just a symptom. Something else is the bottleneck on speed. Could be the OS and drivers used for computer. Reload the driver files for your computer model or motherboard. Is your connection by wifi, or cable to modem? Who is your provider? I had a problem and my verizon ONT needed upgrading. Is it cable all way to home, or FIOS which then goes to ONT and MOCA conversion to cable?

Post was last edited on May 19, 2019 5:13 PM PDT

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Did the techs explain what speed you are paying for?

The 100 is not to the Internet but just from you to their network. After that it's a *rapshot if you will get to/from the Internet at 100. Their network SHARES some Internet connection with everyone on their network so with the huge load of Netflix and more, I rarely see anyone get 100 if they are on an 100 plan.

This has caused a lot of lost time as techs generally don't bother to tell you the ugly truth.

Also, there are folk that want to get all uppity about that. If you do, you will be joining some Internet chorus.

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I just checked mine

It's rated 100 MBs verizon FIOS service and get 70 download, 50 upload.

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Here's an example.
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what does this show?

go to and type speedtest in the search box. A speedtest box will show. You can see what speed you get when it seems to have slowed down. Post the results.

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Additional Info...

So I have 3 TCL Roku TV's, 1 hard wired, 2 wifi. The wifi ones test around 25-30 Mbps down. We have 3 smartphones, 2 S10+ and an iPhone 7, and I run the Speedtest app with the same results on all phones, it quickly hits 110 Mbps then gradually falls, ending in the 20's. We have 2 laptops, one we never really use, the other is my work laptop and I connect at home often but with little to no issues. So in total like 7 devices, probably never more than 4-5 running at the same time.

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100 divided by 5 = 20

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Stop streaming at UHD 4K. Netflix here on my UHD 4K is fed 1080p and it looks great. Only need 5 megabits for that.

Speed testing must be done with the device you want to test having a MONOPOLY!

There's more. To really do well we need a nice router. Current firmware, Gigabit ports, 802.11ac (don't mix in old WiFi during testing, in fact, don't test on WiFi).

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