CM1200 Modem Not Getting Proper Speeds

[IT-Thomas]

I just recently moved into a new apartment and had to change ISPs (I was using Xfinity, but since they don't service the area I'm in I had to switch to Breezeline).

I signed up for their 1Gbps service and for the first week everything seemed to be working great, then all of a sudden my speeds dropped significantly. I did all the standard troubleshooting steps:
  - Checked and verified physical connections were secure and there weren't kinks or damage to any of the cables.

  - Power cycled both my router and my modem

  - Checked my PC for updates and verified that the latest Ethernet drivers are installed.

I then checked my router for a firmware update and lo and behold it needed one so I did it. I then contacted the ISP and requested that they check to see if my modem needed a firmware update. It did, so I had them perform it. My CM1200 is now on firmware version 3.02.01 and I can't get more than 8Mbps on it.

I read some other threads here and attempted various suggested troubleshooting steps including switching the coaxial cables, ensuring there aren't splitters between the modem and the main line, multiple power cycles, and it's still not getting the right speeds.

Do I need to replace my modem?

[FURRYe38]

Please post a copy and paste of the modems connection status and event log page.
https://kb.netgear.com/30007/How-do-I-obtain-the-cable-connection-information-from-a-NETGEAR-cable-m...
https://kb.netgear.com/30008/How-do-I-view-or-clear-the-event-logs-on-my-NETGEAR-cable-modem-or-mode...

Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 
What is the brand and model of the host wifi router connected to the modem?

Have the ISP check the signal and line quality UP to the modem. Be sure the ISP provisions the modem correctly.
Be sure there are no coax cable line splitters in the between the modem and ISP service box. 
Be sure your using good quality RG6 coax cable up to the modem. 
Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, loose connections, bad/old/cheap connectors, or corroded connections. Replace them if you do.
Be sure to power OFF the modem for 1 minute then back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...
https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router
https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html

[IT-Thomas]

[Kitsap]

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@IT-Thomas wrote:

I just recently moved into a new apartment and had to change ISPs (I was using Xfinity, but since they don't service the area I'm in I had to switch to Breezeline).

I signed up for their 1Gbps service and for the first week everything seemed to be working great, then all of a sudden my speeds dropped significantly. I did all the standard troubleshooting steps:
  - Checked and verified physical connections were secure and there weren't kinks or damage to any of the cables.

  - Power cycled both my router and my modem

  - Checked my PC for updates and verified that the latest Ethernet drivers are installed.

I then checked my router for a firmware update and lo and behold it needed one so I did it. I then contacted the ISP and requested that they check to see if my modem needed a firmware update. It did, so I had them perform it. My CM1200 is now on firmware version 3.02.01 and I can't get more than 8Mbps on it.

I read some other threads here and attempted various suggested troubleshooting steps including switching the coaxial cables, ensuring there aren't splitters between the modem and the main line, multiple power cycles, and it's still not getting the right speeds.

Do I need to replace my modem?

---

Not necessarily.  What router (brand and model number) do you have connected to your modem?

You have made firmware updates to two of the major components of your LAN.  You need to power down your LAN, then power it up sequentially to allow the connections to be re-established.

Power down your modem, disconnect the power cord, the coax cable, and the Ethernet cord to your router.  Wait a minute, connect the coax cable and the power cord and allow your modem to fully boot and stabilize.  One of the last indicators to illuminate will be the one for internet. 

Power down your router, disconnect the power cord and the Ethernet cord to your computer.  Wait a minute.  Connect the power cord Ethernet cord to your modem and start up your router.  Give it plenty of time to fully boot and stabilize.  One of the last indicators to illuminate will be the one for internet.

Reconnect the Ethernet cable to your computer and restart the computer.

Recommend you use the Ookla native application on your computer to test throughput.  Avoid using a web browser test.

[FURRYe38]

Power levels are too high. -7Dbm is max for the CM series.

You have Criticals nad Warnings that the ISP needs to review and resolve. 

[IT-Thomas]

I'm using a Nighthawk AX1800 WiFi 6 Router (RAX10)

I usually get 600-750 Mbps WiFi speeds, and I just conducted a test and only got ~240Mbps

Ethernet test (PC to modem directly) peaked around 290 Mbps

I've also attached an updated screenshot of the cable connection status.
I should note that to get the power levels to a reasonable level, I had to reinstall the splitter (the technician mentioned that the power level was too high and installed the splitter to assist that), so do I need to talk to the ISP about fixing the power level so that I don't need the splitter?

[FURRYe38]

Thats much better. 

No correct or un-correctables. Thats good. 

Can keep that on or ask the ISP about a in line attenuator modulal to put behind the modem or at there connection box outside. I've got one mine as well. I use it with my CM1200 and CAX80. 

[IT-Thomas]

I'm still experiencing issues with my modem's speeds.

I should also note that my Netgear Nighthawk app's speed test output a speed of over 800Mbps for the WiFi, even though Ookla only showed about 230-250 Mbps.

This is an updated screenshot of my event log. Anything else I can try? Would you recommend a factory reset

[FURRYe38]

What do you see with a wired PC connected to the back of the modem, no wifi router in the middle and using Ooklas installable speed test app? 

Those Criticals and Warnings have to be looked at by the ISP. 

[IT-Thomas]

Whatever the issue was it finally seemed to resolve itself.

Last test I did had me over 900 Mbps...so Idk what happened or how it resolved.

[FURRYe38]

Ok. 

I'd still have the ISP look at those Criticals and Warnings. 

Enjoy.