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asl2
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Monday, December 8th, 2025 12:15 AM

Modem keeps rebooting

We had an outage Comcast notified us of on December 3rd and 4th.  Ever since then, our modem has been rebooting every 5-15 minutes or so.  I've tried unplugging the modem for a minute and then plugging it back in.  It is an Arris G18 I own.  Is it possible this is a side effect of the outage?

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5 days ago

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asl2

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10 days ago

Here is the WAN status I got from the modem when it was connected (IP / Mac addressed redacted)

Internet:Active
Local time:2025/12/07 18:13:28
System Uptime:0d 0h 7m 49s
WAN IP Address (IPv4): xxxx
WAN Default Gateway Address (IPv4):73.75.44.1
WAN IP Address (IPv6): xxxx
WAN Default Gateway Address (IPv6):fe80::201:5cff:fe68:da46
Delegated prefix (IPv6):2601:240:c484:fbd0::/60
Primary DNS Server (IPv4):75.75.75.75
Secondary DNS Server (IPv4):75.75.76.76
Primary DNS Server (IPv6):2001:558:feed::1
Secondary DNS Server (IPv6):2001:558:feed::2
WAN Link Local Address (IPv6):xxxx
DHCP Client (IPv4):Enabled
DHCP Client (IPv6):Enabled
DHCP Lease Expire Time (IPv4):0d 1h 24m 59s
DHCP Lease Expire Time (IPv6):0d 1h 34m 23s
WAN MAC: xxxx
CM MAC:[Edited: "Personal Information"]
Interface:DOCSIS

Initialization Procedure

Initialize Hardware:Complete
Acquire Downstream Channel:Complete
Upstream Ranging:Complete
DHCP bound:Complete
Set Time-of-Day:Complete
Configuration File Download:Complete
Registration:Complete

Cable Modem

HW Version:1.0
Vendor:Vantiva USA, LLC
BOOT Version:CGR2.86C.727888.R.2310061630
Core Version:0.0.0.0
Model:G18
Product Type:G18
Flash Part:462 MB
DOCSIS FW Version:AC01.01.002_032624_G1X.08.07.735.CT
Serial Number:[Edited: "Personal Information"]
DOCSIS Operating Mode:3.1

Downstream QAM

Index Frequency (MHz) Power Level (dBmV) SNR (dB) Modulation Lock Status
17 507 8.699997 40.366287 QAM256 Locked
14 489 8.699997 40.366287 QAM256 Locked
15 495 8.500000 40.366287 QAM256 Locked
16 501 8.099998 38.983261 QAM256 Locked
18 513 8.500000 40.946209 QAM256 Locked
19 519 8.900002 40.946209 QAM256 Locked
20 525 8.300003 40.366287 QAM256 Locked
21 531 8.300003 40.366287 QAM256 Locked
22 537 8.900002 40.366287 QAM256 Locked
23 543 8.400002 40.366287 QAM256 Locked

Downstream OFDM

Index FFT Type Channel Width (MHz) # of Active Subcarriers First Active Subcarrier (MHz) Last Active Subcarrier (MHz) Avg RxMER Pilot (dB) Avg RxMER PLC (dB) Avg RxMER Data (dB) Power Level (dBmV) Modulation Lock Status
1 4K 92 1840 673 766.95 48 42 42 8.800003 QAM4096 Locked

Upstream QAM

Index Frequency (MHz) Power Level (dBmV) Channel Type Symbol Rate (KSym/sec) Modulation Lock Status
8 22.8 36.770599 US_TYPE_ATDMA 5120 KSym/sec 64QAM Locked
10 40.4 35.260300 US_TYPE_ATDMA 2560 KSym/sec 64QAM Locked
9 16.4 36.520599 US_TYPE_ATDMA 5120 KSym/sec 64QAM Locked
7 29.2 37.020599 US_TYPE_ATDMA 5120 KSym/sec 64QAM Locked
6 35.6 36.770599 US_TYPE_ATDMA 5120 KSym/sec 64QAM Locked

Upstream OFDMA

Index First Active Subcarrier (MHz) Last Active Subcarrier (MHz) Symbol Rate (KSym/sec) Power Level (dBmV) Lock Status Modulation
There is no data to display.

CM Error Codewords

Index Unerrored Codewords Correctable Codewords Uncorrectable Codewords
17 17528738 1 0
14 16422052 1 0
15 16427142 0 0
16 16431635 0 0
18 16436168 0

(edited)

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XfinityQue

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303 Messages

8 days ago

 

asl2, hello there! Thanks for reaching out. I totally understand your concern. I wouldn't be able to confirm that could be a side effect, but have you logged into your modem to see if it has been updated? 

 

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asl2

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@XfinityQue​ I'm not sure where I would find that information.  Here's the software versions:

System Software Version

Gateway FW Version:AC01.01.025_011525_G1X.08.02.735.CT.OTT
RDK-B-LLC:rdkb-2022q1-dunfell
SDK:7.35.0.134
Wi-Fi Driver:WLAN6.2.0.160
(This is for the Arris G-18.)

Here's the first page of the event log, in case that is helpful.  Thanks!
REGISTRATION COMPLETE - Waiting for Operational status;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:50:51 Notice
MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:50:44 Warning
CMSTATUS:US_Diplexer_Mode_Change:[TLV-84.1], [5-42MHz];CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:50:44 Notice
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:[TLV-84.3], [1002MHz];CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:50:42 Notice
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:[TLV-84.2], [108MHz];CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:50:42 Notice
REGISTRATION COMPLETE - Waiting for Operational status;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:43:05 Notice
MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:42:57 Warning
CMSTATUS:US_Diplexer_Mode_Change:[TLV-84.1], [5-42MHz];CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:42:57 Notice
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:[TLV-84.3], [1002MHz];CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:42:55 Notice
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:[TLV-84.2], [108MHz];CM-MAC=[Edited: "Personal Information"];CMTS-MAC=[Edited: "Personal Information"];CM-QOS=1.1;CM-VER=3.1; 2025/12/09 18:42:55 Notice

(edited)

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8 days ago

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XfinityQue

Official Employee

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303 Messages

 

asl2, thanks for sharing. I would not be able to help you determine that as the device is yours, not ours. I would recommend reaching out to the manufacturer to get details on that matter first. That's not anything I can verify since it is not our equipment. That's just the first step needed so we are able to proceed. 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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8 days ago

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asl2

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I checked https://arris.my.salesforce-sites.com/consumers/articles/knowledge/Upgrading-Firmware-on-Cable-Devices and it claims that firmware updates are distributed by the operator (in this case, Xfinity) and they have limited visibility into what versions you have qualified and are currently distributing.  Is there any way you can check which versions you are distributing?  I would be happy to roll back if you think that would help but that article suggests the rollback is something only Xfinity can do.  Thanks!

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8 days ago

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XfinityBenny

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1.2K Messages

@asl2 Good question, we would only update or change the boot files. They determine the speed for the modem, and are changed when the speed changes. The firmware comes from the manufacturer, they normally update online automatically through the ISP connection. Follow the steps here https://www.xfinity.com/support/articles/internet-connectivity-troubleshooting to troubleshoot and ensure the connection is fixed. 

(edited)

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

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8 days ago

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asl2

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I contacted Arris support (my cable modem is a G18 from them).  They say "

Based on the information you shared, the upstream signal levels are not within the acceptable range, which could be one of the reasons the modem keeps rebooting. For your reference, please check the following link on how to verify cable signal levels.

https://arris.my.salesforce-sites.com/consumers/articles/knowledge/G18-G20-Cable-Signal-Levels

The cable signal levels displayed on the interface page reflect the signals being transmitted by your Internet Service Provider (ISP).

We suggest contacting your Internet Service Provider (ISP) to have them reviewed and adjusted as needed."

I also worked through the troubleshooting procedure you mentioned and scheduled a service call for Friday 

 

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7 days ago

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