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Modem signal levels

I Plan to Stick Around

Might one of you who know a lot about cable signals be able to have a look at my signals and tell me how they look? I've noticed severe internet slowdowns and hangs in the last couple weeks, and I've seemed to notice is that my SNR went down 1 db, but I'm not too sure if the signals were bad to start.



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Re: Modem signal levels

Retired Moderator
Retired Moderator

Hello Gurkamal,


What kind of speeds were you getting when you took the screenshot? Do you have the same problem when connected via Ethernet cable and WiFi?  How often do you notice the issue?  Does there seem to be any pattern i.e. specific times?


Is anyone in the community able to help Gurkamal further with his issue?





Re: Modem signal levels

I'm a Senior Contributor

Acceptable modem power levels:

•Receive/Downstream: -15dbmV to +15dbmV

•Transmit/Upstream: 30dbmV to 53dbmV

•Signal to Noise Ratio(SNR): 33dB or Greater


Be aware Rogers has been doing network maintenance for the past couple months. Upstream channel count and power levels are currently unstable and vary day to day. Issues are localized but reportedly widespread across Ontario.


Unstable Signal Levels WILL CAUSE disconnects. Speed drops have also been occurring from time to time.

Yea I know, this post is total "Hogwash"

Re: Modem signal levels

I Plan to Stick Around

I do get the speeds I should, but often times (a coupe every day), my internet starts to hang, sometimes ranging from for a few seconds to a minute or two, or either it'll slow down to an absolute crawl for the same time period. My DOCSIS event log on my modem will then give me either a T4 timeout or a MDD timeout (I suppose those are the disconnection messages). I'm also unable to bridge the modem anyhow because my router doesn't seem to want to work with it, meaning that the problems occur both over ethernet and wifi. The problem also appears randomly (no specific timing).



Re: Modem signal levels

I've Been Here Awhile

We've been having power level issues on our DPC3825 for a while now, but today they really took a nosedive. I'm wondering if the temperature and humidity are a factor, because the problems started when winter ended and are at their worst today (26C and the most humid I think its been since winter).




Prior to things escalating to where they are today, downstream for all channels was sitting at about -5 dBmV, which is about what I expect with one Rogers installed splitter before the modem in our current setup.


Nothing in the house has changed. We had a less serious but similar issue early last year but that was resolved when a tech came and looked at the outdoor equipment.


We're currently still on Hi-Speed Express Unlimited and have intentions to switch to Ignite 100 since it's a bit cheaper and significantly faster, but I'd like to resolve our signal issues first if I can.


I've had the modem directly connected to the computer. I've power cycled it and my router on three separate occasions since Friday when things started to get really slow. I've restarted my computer at least twice just today. I know none of these things are the problem.


Before I schedule a tech visit is there anything else I should try?

Re: Modem signal levels

Looks like you have a cable and / or connector failure in progress.  Your upstream levels are bumping up against the upper 51 dBmV limit.  Above that and you lose upstream channels.  When that happens you will really see the data rates slow down.  Call tech support and have the CSR run a signal check on your modem.  The outcome of that check should be a tech visit to inspect and probably change out the external cable and connectors.  Fwiw, our inground cable performed really well right up to the day that it died.  Tech came in, replaced the cable, and everything was back to normal.  The cables don't last forever, and every once in a while, need replacing.  That's a normal occurrence.

Re: Modem signal levels

Modem signal check


I recently just got ingite 100u. I was CGN3ACSMR with firmware version  was checking my signal levels for what's acceptable based on this post from 2013 which I hope is still applicable and just wanted some confirmation that things are okay. I do see that many of the acceptable postings have the downstream signal strenth around 0. 
I am not noticing any disconnections and speedtest show good speeds of around 130/11 but I do see these messages in the modem's logs
critical - No Ranging Response received - T3 time-out
error - DHCP RENEW WARNING - Field invalid in response v4 option
Also, on the upstream is it normal for channel 5's bandwidth to be 3200000 vs 6400000?


Downstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID Signal noise ratio (dB)
1 651000000 256QAM 5.900 106 38.605
2 591000000 256QAM 7.100 97 38.983
3 597000000 256QAM 7.400 98 38.983
4 603000000 256QAM 7.400 99 38.983
5 609000000 256QAM 7.000 100 38.605
6 615000000 256QAM 6.700 101 38.605
7 621000000 256QAM 6.500 102 38.605
8 633000000 256QAM 5.900 103 37.636
9 639000000 256QAM 5.900 104 37.636
10 645000000 256QAM 5.900 105 38.605
11 657000000 256QAM 5.800 107 38.605
12 663000000 256QAM 5.900 108 38.605
13 669000000 256QAM 5.900 109 38.605
14 675000000 256QAM 5.800 110 37.636
15 681000000 256QAM 5.600 111 38.605
16 687000000 256QAM 5.500 112 37.636
17 693000000 256QAM 5.400 113 37.636
18 699000000 256QAM 5.700 114 38.983
19 705000000 256QAM 5.700 115 38.605
20 711000000 256QAM 5.800 116 38.605
Upstream Overview
Port ID Frequency (MHz) Modulation Signal strength (dBmV) Channel ID BandWidth
1 38596000 ATDMA - 64QAM 42.250 5 3200000
2 23700000 ATDMA - 64QAM 42.250 7 6400000
3 30596000 ATDMA - 64QAM 42.250 6 6400000

Re: Modem signal levels


Hello, @unknownsubject


Welcome to the Rogers Community Forums! Smiley Happy


Thank you for your detailed post. Ideally, for the Downstream, the signal strength should be at 0 dBmV but the acceptable range is between -10 dBmV and +10 dBmV and for Upstream the range is between 35 dBmV and 52 dBmV. So the signal at your modem is with in the specs. The Upstream channels can lock into to either 32/6400000. Regarding T3 timeouts, it's the modem communicating with the CMTS and when it doesn't receive a response it's documented in the log file for troubleshooting purposes.


It's good to know that you are getting speeds better than 100u package speeds, hope you are enjoying your Internet experience.




Re: Modem signal levels

I've Been Here Awhile

Hi Guys,


New 250u install today. Speed is great averaging over 300 down and 20 up. I keep getting random hang ups/time out when browsing the web. It doesn't seem to affect streaming, Skype, VoIP etc. It's happening on and off and is anything but consistent. I've tried different DNS servers and that doesn't seem to be helping at all.


I spoke with tech support and they said it looks like a problem with the modem signals. Can someone look at these and tell me if they're okay?


1 639000000 256QAM 1.000 128 38.983
2 591000000 256QAM 1.200 121 38.983
3 597000000 256QAM 1.400 122 38.983
4 603000000 256QAM 1.300 123 38.983
5 609000000 256QAM 1.300 124 38.983
6 615000000 256QAM 1.600 125 38.605
7 621000000 256QAM 1.400 126 38.983
8 633000000 256QAM 1.100 127 38.605
9 645000000 256QAM 0.800 129 38.983
10 651000000 256QAM 0.800 130 38.983
11 657000000 256QAM 0.700 131 38.605
12 663000000 256QAM 0.600 132 38.605
13 669000000 256QAM 0.200 133 38.605
14 675000000 256QAM 0.200 134 38.605
15 681000000 256QAM 3.500 135 40.366
16 687000000 256QAM 3.400 136 40.946
17 693000000 256QAM 3.300 137 40.366
18 699000000 256QAM 3.500 138 40.366
19 705000000 256QAM 3.800 139 40.366
20 711000000 256QAM 3.500 140 40.366


1 30596000 ATDMA - 64QAM 41.500 2 6400000
2 23700000 ATDMA - 64QAM 41.500 3 6400000
3 38596000 ATDMA - 64QAM 41.500 1 3200000


I haven't used a cable Internet connection in years so I'm not sure what is considered good/acceptable.


Any help would be appreciated as I work from home and need a stable connection.


Thanks in advance!



Re: Modem signal levels

While there is a little fluxuation 1-0-3, which is a little odd.. its pretty close to spec.
You want to have as close to 0.. normally wouldnt see a lot of issues signal related till you got up 8+/- or greater in my experience.


Nothing that should be causing what you are experiencing.


DNS would have been my first guess.. but you said you have tried that as well.

Re: Modem signal levels

I've Been Here Awhile

Thanks Gdkitty for the response. That's what I thought, the signals don't seem too bad. Speeds are fine.


I've tried to update the DNS servers to Google's DNS and Open DNS, but the connection stops working completely whenever I change the setting to manual and enter the new server information. Seems like there is a bug in the firmware? Anyone know if this is a known issue?


The sporadic dns behaviour doesn't seem as bad today, but pages do still feel like they are taking longer to resolve than they should.


Thanks again.


Re: Modem signal levels

So your trying to change the DNS on the router side?

Never done that myself..

I run the google DNS, but i set it on a device by device bassis.

You could try setting it on the specific device itself, see if that makes a difference?

Re: Modem signal levels

I've Been Here Awhile

Yeah, I have tried changing it on the router side but it causes the Internet to completely stop working.


I've set the DNS on my devices to Google and it seems to have helped a bit. Still seeing slow page loading but it's tolerable.

Re: Modem signal levels

I've Been Here Awhile

I've been having this issue with my CGN3ACSMR


I've been experiencing this problem with my internet. It disconnects constantly and can never go a day without disconnecting, sometimes it stays disconnected and doesn't come back up. I've tried alot of things (replaced the surge protector, plugged router directly into the wall, thought maybe it's a wifi problem but same thing with a wired connection aswell, I've also hooked it up in Bridge mode and connected it through a R7000 modem) but still no luck, keeps disconnecting. Decided that I need some help from the community in figuring this out as it's very frustrating.

Here's what DOCWAN says:

Downstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDSignal noise ratio (dB)
Upstream Overview
Port IDFrequency (MHz)ModulationSignal strength (dBmV)Channel IDBandWidth
138596000ATDMA - 64QAM35.18053200000
223700000ATDMA - 64QAM33.75076400000
330596000ATDMA - 64QAM33.75066400000

Re: Modem signal levels

Your downstream signal levels are high, signal to noise is good.  The upstream signal levels are low.  Usually the downstream is at or around 0 dBmV with a signal to noise ratio in the 36 to 40 dB range, and the upstream is in the 36 to 40 dBmV range.  Are you in an apartment, condo, highrise, etc, etc, by any chance?

Re: Modem signal levels

I've Been Here Awhile

I'm in a detached house, using a wired connection going down to a basement.

Re: Modem signal levels

1.  Are you running more than one Rogers device, ie, Internet modem, Cable Box, Home Phone?


2.  Can you check where the cable enters the house and see if there is a "powered" inline amplifier installed that connects to all of the other devices.  If there is one, that would explain the high downstream levels.  The old style amps amplify everything and cause packet loss.  The new amps have a non-amped port which is used for VOIP devices and the Internet modem.


Edit:  If there is no power brick attached, you would have a non-powered multi-port splitter if there is more than one Rogers box in the house.  That would drop the power levels for every attached device, and if that is what you have, its interesting that your power levels are still as high as they are.

Re: Modem signal levels

I've Been Here Awhile
Thank you, I didn't know that and will go home and check out on that.

I have the Internet modem, then through that I have vonage, android streaming box, chromecast, cellphones, etc. So everything is connected through the rogers router.

Re: Modem signal levels

I've Been Here Awhile

Actually signal level should be as follows

TX :35 to 51dBmV 

RX: -10 to 10

SNR: over 25


You can pull these from your modem web page under Status | DOCSIS WAN and use attenuators to adjust the numbers

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