Re: +9dB downstream not good enough?

adossant · ‎2023-08-08

Connection troubleshooting states "Good Downstream power levels are within -7 to +7 dBmV". However, even at +9dB, my CM1150V was not providing a solid link, my router was frequently loosing connectivity (often displayed a red link light and we experienced poor wifi performance). Yet when I removed the 3-way splitter, bringing the downstream power up to 13dB, now it is working fine. Note an Xfinity modem worked fine with the 3-way splitter over an extended six to nine month period, no problems (sadly, when the Netgear was not doing the job, I had to pay $75 for a service call and they hooked up their modem, and then it worked fine).

FURRYe38 · ‎2023-08-08

+9dB is too high:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

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?

adossant · ‎2023-08-09

Thank you for your response. Yes, I did see that. However, if +9dB is too high, then why does +13dB work flawlessly? Since removing the 3-way splitter increased the power to +13dB, it has worked flawlessly. I haven't had a single disconnection. I have to get ready for work, but I am attaching a snapshot of my connection status while I was experiencing the difficulties. I'll see about getting the log tonight. Thanks again.

plemans · ‎2023-08-09

If it works fine without the 3 way connector, I'd really be suspicious of the 3 way connector.

You can run your signal hot but it can cause issues and longevity problems.

that's why we recommend it at lower levels.

adossant · ‎2023-08-09

I see. (Although that same 3-way splitter worked fine with the Xfinity modem). Ok, is there a specific 3-way splitter that is designed to function with the CM1150V? (i.e. can you recommend one that should work with it)? Thank you for your assistance!

plemans · ‎2023-08-09

Most decent quality ones should be fine. Its not always the splitter. It could be the end connector that it doesn't have caps on it, not being tight enough, etc.

I used to run around that same 13-14dbmv and it worked fine. Then I started to get errors so I used to just use a 4x way splitter for a while but then it started having errors. so I just picked up a signal attenuator and connected that in line. Has been working fine for around 6-8 months. They're not to expensive. I think I picked up a 3,6,9 dbmv attenuator so I could play around with the signal levels.

adossant · ‎2023-08-10

Thank you plemans. The 3-way splitter was a brand new one installed by Xfinity. And they did also install, I believe it was an attenuator outside the house. All of the cabling was new, all the way out to the pole. I will try to find the best 3 or 4 way splitter I can, and see if that one works. I was just looking at this Amphenol splitter on Amazon (https://www.amazon.com/AMPHENOL-IPGH3M4-VF-Infinity-Premise-Splitter/dp/B07CQTHL33/ref=sr_1_3?crid=1...) that has one -4dB hybrid output, 2x -7.5dB hybrid outputs, as well as 4 -12dB MoCA outputs. If it's truely Amphenol, I believe it should be of good quality. I like that it allows for three different levels of dB reduction and would allow MoCA use in the future.

adossant · ‎2023-08-19

UPDATE 19AUG2023: I received and installed the Amphenol IPGH3M4-VF splitter. I can achieve a solid internet connection using the -4dB H1 port which yields downstream channel power ranges of 10.1-11.2dBmV. I tried one of the -7.5dB ports which yields downstream channel power ranges of 6.8-8.3dBmV however the internet connection is then very poor. It was also poor using the -5dB port on the new 3-way splitter Xfinity had installed. It is confusing to me that the modem is supposed to prefer -7dBmV to +7dBmV, but my particular modem performs poorly below +10dBmV. Does that indicate my modem is faulty? Thanks all... AL

adossant · ‎2023-09-04

I was experiencing poor connectivity using a 1yr old, 3-way splitter installed by Xfinity. It worked fine using their modem but using my CM1150V my connection was poor despite downstream channel power levels of 8.2-9.8dBmV and SNR of 42-43dB.

I tried it using no splitter and the connection was then fine, but power levels were up to 13-14dBmV and forum members suggested that it too high as -7 to +7dBmV is suggested.

One on here suggested it could be the 3-way splitter. So I installed a new Amphenol IPGH3M4-VF splitter. I can achieve a solid internet connection using the -4dB H1 port which yields downstream channel power ranges of 10.1-11.2dBmV. I tried one of the -7.5dB ports which yields downstream channel power ranges of 6.8-8.3dBmV however the internet connection is then very poor. It was also poor using the -5dB port on the 3-way splitter Xfinity had installed. It is confusing to me that the modem is supposed to prefer -7dBmV to +7dBmV, but my particular modem performs poorly below +10dBmV. Does that indicate my modem is faulty? Thanks all... AL

FURRYe38 · ‎2023-09-04

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...

FYI:

https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

Kitsap · ‎2023-09-04

Are you using the proper termination caps on the unused splitter connections?

Link from Amazon: https://a.co/d/eClKMrs

plemans · ‎2023-09-07

it could just be using the splitter as well and not a signal attenuator.

That splitter is a bit fancy and not your typical splitter. Could be doing some filtering thats causing issues.

adossant · ‎2023-09-07

Hi Plemans. Thank you for your feedback. My CM1150V was also not working well at all with the more basic 3-way splitter Xfinity had installed (which was brand new). And it also does not work well using a -7.5dB port of the Amphenol splitter, but it's been working fine with the -4dB port on the same Amphenol splitter. I did order and received 10 of the port terminations recommended (ty Kitsap for that recommendation). So I am going to install seven of those tomorrow and can try one of the -7.5dB ports again, after terminating all of the others. I will also work to get those log files etc.. I am off tomorrow so will have more time to work on this then. Thanks again to all, I really appreciate the support!... AL