Question

SVG2482AC periodic DNS failure across entire LAN - Bridge mode

  • 29 December 2022
  • 3 replies
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We are experiencing periodic DNS failures on our network.
We are Xfinity customers,  The SVG2482AC Surfboard modem is in bridge mode.
I have checked the power levels as recommended in another thread,  all look ok.

We are using an ASUS Wifi router RT-AX3000 (switched back to older RTX56 for testing)
we have updated, reset, tested to no avail.
the failure appears as webpages suddenly will not refresh,  and usually we receive a DNS response error.  the  failure resolves in 10-30 seconds. this happens to ALL phones and laptops at the same time, whether wired or Wifi.

I cannot find anything in the modem nor router logs to explain.
Traceroute results are inconclusive.  

Here’s the QUESTION:  will/can a modem in “Bridge Mode” interfere with DNS requests?  


I have not reached out ComCast yet because , well, Comcast...

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Hello melaniedawn2017

                                             When enabling Bridge mode on any gateway which is the combination of modem and router will not interfere DNS request since it will just act as a cable modem so If any issue on Wi-Fi or Wi-Fi connected devices you need to check only on the router setting page or you can reach out to router manufacturer for more assistance on Wi-Fi when you are using different router connected to the gateway.

Let us know if this helps.

SURFboard Community Moderator Team
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Thank you, that is helpful information.
While troubleshooting this problem, I have found a couple odd things in the logs.
1 - There are no “System” logs available.  is this normal for bridge mode?
2 - no Firewall logs, I assume not relevant in Bridge mode as we are not using the Wifi.
3 - The event logs are never newer than yesterday.
4 - When I pull the event logs for the last 90 days, they present out of date order

On page 3
Dhcpc][1571]: mta0 T1 Expired, Enter Renew State    2023/1/01 05:50:06    Notice
[Dhcpc][1696]: erouter0 T1 Expired, Enter Renew State    2023/1/01 00:48:46    Notice
[Dhcpc][1941]: erouter0 T1 Expired, Enter Renew State    2022/10/31 18:31:21    Notice
[Dhcpc][1941]: erouter0 T1 Expired, Enter Renew State    2022/10/31 17:28:08    Notice

On page 10
[Dhcpc][24157]: mta0 T1 Expired, Enter Renew State    2022/10/14 12:59:05    Notice
[Dhcpc][24448]: erouter0 T1 Expired, Enter Renew State    2022/10/13 17:31:55    Notice
[Dhcpc][1732]: erouter0 T1 Expired, Enter Renew State    2022/11/30 18:44:40    Notice
[Dhcpc][1582]: mta0 T1 Expired, Enter Renew State    2022/11/30 17:42:17    Notice

On page 20
[Dhcpc][1941]: erouter0 T1 Expired, Enter Renew State    2022/10/31 19:40:08    Notice
[Dhcpc][1696]: erouter0 T1 Expired, Enter Renew State    2022/12/31 12:48:45    Notice
[Dhcpc][1696]: erouter0 T1 Expired, Enter Renew State    2022/12/31 00:48:46    Notice
[Dhcpc][1696]: erouter0 T1 Expired, Enter Renew State    2022/12/30 12:48:46    Notice

5 - Should these be happening so often?

[Dhcpc][1951]: erouter0 T1 Expired, Enter Renew State    2023/1/05 07:14:40    Notice
[Dhcpc][1951]: erouter0 T1 Expired, Enter Renew State    2023/1/05 06:05:00    Notice
[Dhcpc][1951]: erouter0 T1 Expired, Enter Renew State    2023/1/05 04:58:12    Notice
[Dhcpc][1951]: erouter0 T1 Expired, Enter Renew State    2023/1/05 03:49:16    Notice
[Dhcpc][1951]: erouter0 got new IP (redacted)    2023/1/05 03:31:13    Notice
[Dhcpc][1842]: mta0 got new IP (redacted)    2023/1/05 03:30:40    Notice
[Dhcpc][1696]: erouter0 T1 Expired, Enter Renew State    2023/1/05 02:47:44    Notice
[Dhcpc][1696]: erouter0 T1 Expired, Enter Renew State    2023/1/05 01:37:11    Notice
 

6 - I believe that when I checked the stats all looked ok, but the Uncorrected codewords are a problem
 

 

7 - Does any of this reflect as faulty hardware?  I want to dot all my I’s, cross my T’s before I contact Xfinity, as they will try to blame my hardware.

Thanks in advance

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UPDATE

I reached out to Comcast support.
The tech was able to see some line problems so they sent out a tech without too much fuss. (I was worried that they might try to charge me)
Service tech arrived the next day,  he said the outside line felt “crunchy” lol.
Long story short he replaced everything from the pole to the splitter inside the house.
he also told us that the connection at the pole was in bad shape, also.
All seems good again.

I will add a final update in a week, But it feels like its fixed.
 

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