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Internet keeps dropping. Is it my modem?
Cable TV is not affected, but for about a month now (or more), we lose internet connection once a day. Now it’s happening a few times a day, sometimes back-to-back. The cable MODEM is my own-–a Motorola SBG6580 modem/router (maybe over 5 years old). I’m looking into getting a new modem, but am curious if the modem is even the problem.
When the internet goes out, we can still see our Wi-Fi network as available for a few minutes (all modem lights are on), then all the lights on the modem go out and the connection is reset in about five minutes.
I have not contacted Comcast about this issue, other than this post (assuming that my modem would be blamed).
No reported outages in the area, and I tried restarting the modem using the online troubleshooter and leaving it unplugged overnight.
I tried switching to a wired/ethernet connection, but I still had the problem. I removed the splitter (in the room) and connected the modem to the cable, but I still had the issue. I also connected the modem in a different room (downstairs) and still had the issue.
We don’t use much bandwidth--we use a Roku for Netflix for a few hours only, and have a computer connected most of the day for browsing/email, etc.
This may be irrelevant, but today I noticed that when my computer re-connected to the internet, it connected to the Wi-Fi extender by default instead of the modem. And the very first week I noticed the Wi-Fi going out, I remember going through the Windows troubleshooter and it said something about the DNS Server.
I’ve seen the information below included on other posts--I don’t know what it all means, but maybe it’s helpful:
********These are repeated over and over in my modem EVENT LOGS:
Mon Aug 09 18:51:37 2021 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0;
Mon Aug 09 18:48:01 2021 Critical (3) 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0;
Mon Aug 09 18:48:01 2021 Critical (3) Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0;
********And I usually see this too, but not as often:
Mon Aug 09 18:33:47 2021 Critical (3) Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0;
********Yesterday, I saw this ABOUT THRITY times on the Event Log:
Sun Aug 08 11:12:17 2021 Warning (5) Dynamic Range Window violation
********And for CONNECTION STATUS, this is what I saw yesterday:
(Upstream POWER numbers in the fifties):
Upstream Bonded Channels
Channel/Lock Status/US Channel Type/Channel ID/Symbol Rate /Frequency /Power
1 Locked ATDMA 4 5120 Ksym/sec 29200000 Hz 54.0 dBmV
2 Locked ATDMA 1 2560 Ksym/sec 10400000 Hz 49.9 dBmV
3 Locked ATDMA 2 5120 Ksym/sec 16400000 Hz 54.0 dBmV
4 Locked ATDMA 3 5120 Ksym/sec 22800000 Hz 54.0 dBmV
********I appreciate any input. Thanks.
Is there something I should add here, or try?
My internet just went out twice as I was finishing typing this, so hopefully I won't need to retype this!
Here are the top entries from the log now:
| Mon Aug 09 20:22:51 2021 | Notice (6) | TLV-11 - unrecognized OID;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Time Not Established | Notice (6) | Honoring MDD; IP provisioning mode = IPv6 |
| Time Not Established | Notice (6) | WiFi Interface [wl0] set to Channel 11 (Side-Band Channel:N/A) - Reason:INIT |
| Mon Aug 09 20:21:29 2021 | Critical (3) | Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 20:17:09 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 20:02:47 2021 | Critical (3) | Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 19:58:27 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 19:42:10 2021 | Critical (3) | Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 19:37:49 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:48:01 2021 | Critical (3) | 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:48:01 2021 | Critical (3) | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:48:01 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:48:00 2021 | Critical (3) | 16 consecutive T3 timeouts while trying to range on upstream channel 2;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:47:59 2021 | Critical (3) | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:47:59 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:47:59 2021 | Critical (3) | 16 consecutive T3 timeouts while trying to range on upstream channel 1;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:47:59 2021 | Critical (3) | Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
| Mon Aug 09 18:47:59 2021 | Critical (3) | Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=[info removed];CMTS-MAC=[info removed];CM-QOS=1.1;CM-VER=3.0; |
XfinityJosephA
Official Employee
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1.3K Messages
3 years ago
@ruebee, most of the time when we see a lot of T3 timeouts this indicates a degraded signal is impacting your connection. I'm sorry you have been losing connection. When you have a moment send us a direct message using the "Direct Message" icon at the top of the page. If you can send your name and service address to "Xfinity Support" we can help! Once we locate your account, we can take a closer look at your SBG6580, signal quality and schedule an appointment if needed.
1
EG
Expert
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105.6K Messages
3 years ago
@ruebee
That's the problem. The upstream power is intermittently fluctuating to too high / out of spec levels ! It should not go over 50dB.
That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
In an effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.
Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.
If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.
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BruceW
Gold Problem Solver
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25.8K Messages
3 years ago
Although probably not the cause of the problem you are seeing, you should be aware that the SBG6580 is no longer a supported device. See https://www.xfinity.com/support/devices/.
(edited)
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some_user
Visitor
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2 Messages
3 years ago
I'm right there with you @ruebee same thing has been happening to me. I haven't caught the power spikes when checking signals, yet.
I have a question for you. Does it happen at specific times or consistent time ranges each day? For me it is almost like clock work right about 2300 (11:00 PM) and then usually sometime between 0900-1000 in the morning. Awfully consistent to just be some cable or splitter issue as humidity, temp and all that vary day to day.
Our numbers are also very similar as well although I'm a bit closer to 0 on the downstream power, from -1.0 to -2.9 across 31 channels. So a bit better off on Signal to Noise.
So modem compatibility or not, yours is working when there isn't signal issues and that seems to be the cause. I'm running a Netgear CM1000.
(edited)
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BruceW
Gold Problem Solver
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25.8K Messages
3 years ago
No, it's because the device is no longer approved at all, for any speed tier. This was clearer in the past when Comcast explicitly listed devices as reaching "end of support", but now we have to infer it. They seem to be dropping support for nearly all 8x4 devices like the SBG6580.
(edited)
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