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G18 on Comcast / Xfinity keeps rebooting

  • December 10, 2025
  • 2 replies
  • 6 views
A
The Many
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After a comcast outage, my G-18 started rebooting every 5-15 minutes.  I have opened a ticket with Xfinitity, but they seem to think the router software might have been updated and that might be the cause of the problem.  They then said that since it is not their router, they cannot help me.  I pointed them at https://arris.my.salesforce-sites.com/consumers/articles/knowledge/Upgrading-Firmware-on-Cable-Devices saying Xfinity as the DOCSIS operator would be updating the software, but they seem to disagree.  Which of you is right?
Here is the thread: https://forums.xfinity.com/conversations/your-home-network/modem-keeps-rebooting/6936189899d8a96371b4e10e
I have posted the software version, WAN status, and Event Logs from the G-18 user interface there.  Does anything stand out to you?

I believe the G18 is rebooting since it does not respond to pings over either wifi or wired ethernet.

 

Thanks!

2 replies

A
The Many
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  • asl2The Many
  • Author
  • The Many
  • December 10, 2025

I’m copying the WAN status / software versions / event logs into this ticket for reference, in case that’s useful:
 

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
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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

 

 

 

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

 

S
Wi-Fi Warriors
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When it comes to firmware updates DOCSIS standards dictate that the service provider must distribute firmware updates to cable modem devices.  The end-user cannot simply install an update like most other network-enabled devices.

ARRIS develops the software update and makes it available to service providers.  The service providers qualify, test, and distribute the software update to devices on their network. ARRIS has limited control or visibility on distribution by the service providers

Could you please confirm your subscribed internet speed plan with your Internet Service Provider?

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.

 

SURFboard Community Moderator Team
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