CM1150V Downlink Light Flashing

[MadDog97]

My CM-1150V Cable Modem has in issue where the downlink light starts flashing, but everything is working correctly.  The modem status shows no issues.

When this happens, I've received two CM-STATUS messages, both for channel 48:  CM-STATUS Event type code 20, and Event type code 22.   Documentation for these events (Cable labs doc) show event 20 is Next Codeword Pointer (NCP) Profile Failure, and event 22 is NCP Profile Recovery.   

I believe that event 22 should stop the downlink light from flashing, but it isn't. 

Can Netgear confirm that this is the case?  My CM-1150V is using firmware version V2.02.04.

Thanks.

[plemans]

Post the entire logs back here plus the cable connections page. That helps more than a single error. 

If there's any spliters, attenuators, or amplifiers in line, remove them. Also check for any damage, kinks, bad/cheap connectors, or extended run with the coax cable. 

[MadDog97]

Here's a screenshot of the error log.  The CM-STATUS 16 and 24 messages don't start the downlink light flashing.

One other data point:  The downlink light *stops* flashing when I receive CM-STATUS 23 and 22 messages.

I do have a splitter in the line, but cannot remove it.  

[FURRYe38]

Have the ISP check the signal and line quality UP to the modem. 
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. 
Be sure to power OFF the modem for 1 minute them back ON.

[plemans]

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@MadDog97 wrote:

Here's a screenshot of the error log.  The CM-STATUS 16 and 24 messages don't start the downlink light flashing.

One other data point:  The downlink light *stops* flashing when I receive CM-STATUS 23 and 22 messages.

I do have a splitter in the line, but cannot remove it. ---Sure you can. Its for testing. If you remove it and the issue goes away, the splitter was the problem. I'd recommend moving the modem to where the coax enters the home anyway. 

---

And did you have the cable connections page? that helps to compare to the logs. 

but as @FURRYe38 said, you'd probably need to have the ISP check the line. It just helps to know why you're having them check the lines when you call. 

[MadDog97]

Here's the cable status.

Cable splitter is on the outside of the house, before it goes into TV room and under house towards the bedrooms.  Therefore, cable modem cannot be placed before the splitter.

[plemans]

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@MadDog97 wrote:

Here's the cable status.

Cable splitter is on the outside of the house, before it goes into TV room and under house towards the bedrooms.  Therefore, cable modem cannot be placed before the splitter.-----Sure it can. get a direct connection adapter and just direct connect it through and send that leg to the modem. If the problem resolves, its a signal issue or the splitter issue. Your not doing this permanantly. You're doing it for testing/troubleshooting. 

---

When the light goes blinking, it means its searching for downstream channels or attempting to lock them. If its solid, their locked. If the screen snip is taken when they're not blinking it just shows the connection at that time. Maybe there's a loose connection, bad cable, or even the wind thats effecting a line. (or something similar) I've had moisture in a coax cable that caused many a headache for troubleshooting. I finally moved the modem to a different line and it worked fine. moved it back, issues. So I replaced it and was checking the line and found a crack/moisture in it. 

How often do you run into the issue? If its daily, use the direct connection without the splitter for that time period. yes you might not have tv for 24-48 hours but its part of testing/troubleshooting. 

Also, what sized splitter is it? 

Usually the recommend route is to split the incoming signal with a dual splitter. You send 1 leg to the modem and use the rest to feed the house. On the house line you can add more/larger splitters but it ensures the best signal sent to the modem.

[MadDog97]

The cable connection page shows the same results, whether the light is blinking or not, and the modem is working fine.

My original question was that I believe the flashing downlink light, caused by a CM-STATUS message Event type code 20,  isn't turned back to a solid light when a CM-STATUS message Event type 22 is posted.  

Now, why I get these errors, I have no idea.  The time between the messages is usually around 30 seconds or so.

[Wallie]

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@MadDog97 wrote:

The cable connection page shows the same results, whether the light is blinking or not, and the modem is working fine.

My original question was that I believe the flashing downlink light, caused by a CM-STATUS message Event type code 20,  isn't turned back to a solid light when a CM-STATUS message Event type 22 is posted.  

Now, why I get these errors, I have no idea.  The time between the messages is usually around 30 seconds or so.

---

 I have the exact problem. Gigabit internet works fine and speedtest results in the 900Mbps range. Not sure why the downstream LED is always blinking. Maybe a firmware bug?

[MadDog97]

That's what I was asking.  Is there a firmware bug that allows the downlink light to keep flashing after an error is cleared.  On another note, the errors seen in my logs have almost disappeared.  I used to get 10 - 20 errors a day, now I see one error every few days.

[FURRYe38]

Has a power OFF of the modem for 1 minute then back on change the LED behavior? 

Try a factory reset as well...

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. 
Be sure to power OFF the modem for 1 minute them back ON.
https://community.netgear.com/t5/Cable-Modems-Routers/General-info-and-Troubleshooting-for-Cable-Mod...

[MadDog97]

I usually just reboot the modem to clear the flashing light.  

Xfinity is totally worthless.  Their answer is to reset my wireless router.   

[Wallie]

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@MadDog97 wrote:

I usually just reboot the modem to clear the flashing light.  

Xfinity is totally worthless.  Their answer is to reset my wireless router.   

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Yes. reset/reboot the cable modem clears the flashing light. However, it will come back in a day or two. 😞 

[Wallie]

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@FURRYe38 wrote:

Has a power OFF of the modem for 1 minute then back on change the LED behavior? 

Try a factory reset as well...

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. 
Be sure to power OFF the modem for 1 minute them back ON.

---

Turning off the modem will clear the flashing downlink light. However, the downlink light will start flashing again in a day or two. 😞

I have a coax splitter between my TIVO box and CM1150V cable modem. I did try bypasing it and connect the coax cable directly to the CM1150V cable modem. Sadly, it did not solve the flashing problem. 😞

According to the CM1150V modem status, my downstream power for all the 32 channels are around +1dBmV and SNR around 37dB. The 4 upstream channels power are around 43dBmV. Both within the recommended DOCIS 3.1 modem specification.

I believe that it's a firmware issue since my internet connection (around the 900Mbps from speedtest.net) and phone line are fine.  

[FURRYe38]

Something to contact the ISP about as well. IF they claim the signal is good, then I would contact NG support. Would be nothing else that can be done here in the forums. 

[MadDog97]

NG support doesn't monitor these forums?   I would think that they (hopefully) have the technical expertise to answer my question.

[FURRYe38]

No. Try a forum moderator:

@olympos1625