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Jason609's profile

Contributor

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13 Messages

Tue, Feb 23, 2021 6:42 PM

DPC3941B Firmware Upgrade Broke IPV6

Comcast pushed a firmware upgrade to my DPC3941B modem last night and broke my IPV6 connectivity. I had asked for help on these forums previously and Tier 2 Support rolled back my firmware back to fix the issue, this was fine until last night. Additionally, the modem has not been stable since the upgrade and keeps rebooting and I can no longer access the modem's internal web server through static gateway IP address. Can you assist with a firmware roll back or device upgrade to fix these issues? 

Responses

Contributor

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13 Messages

2 m ago

Wanted to provide an update since it may be helpful to others. Since I couldn't get any help with my DPC3941B and needed to get my internet working reliably again phone support had it swapped with a CBR-T CGA4131COM. Soooo, IPV6 PD does not work when using my router. It will work for a single /64 if connected to the LAN of the CBR-T but not for setups anymore complicated than that. So basically still have a /56 that I can't use!

I went through this same issue over a year ago and Comcast still has not been able to fix the issue with IPV6 when the CBR-T needs to route. Has anyone at Comcast Business sent this issue to the CPE department? It's pretty crazy that this issue is documented all over these forums and elsewhere and still there are no clear explanations from Comcast as to why this can't be fixed. 

Contributor

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21 Messages

2 m ago

Welcome to the club.

My working hypothesis is that as helpful as customer service would like to be, they don't actually have a way to escalate issues to a network engineer to replicate, diagnose, or address the underlying problems with their equipment.

At this point, I would take my business elsewhere but there isn't anywhere to take it to.

Contributor

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13 Messages

2 m ago

Another Update. So I managed to get IPV6 PD working with my Ubiquiti EdgeRouter 4. After I committed the following I had to unplug the ethernet connection to the CBR-T and reconnect it, then IPV6 started to work, confirmed on test-ipv6.com. The following lines were added to my configuration:

Note: Interface eth1.10 is the LAN, change this to yours. Change Prefix-id for each vlan (if applicable) e.g. :1, :2, :3 and so on. I will update if this continues to work long term.

 dhcpv6-pd {
     pd 0 {
         interface eth1.10 {
             host-address ::1
             prefix-id :1
             service slaac
         }
         prefix-length /59
     }
     rapid-commit disable
 }

Official Employee

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4 Messages

Hello, @Jason609! I'm sorry to hear about the connection issues being experienced with the IPV6 connection after a firmware update was pushed to your modem. I do see that you stated you reached out to us to work on this before but we're still seeing the issue being experienced. I appreciate you already taking steps to try and correct this and I would like to look into this further with you, including going over what has already been done. Please reach out to us through our new Peer-2-Peer feature!

 

There is a Chat Bubble in the upper right corner which will open a new window for us to work with you privately. I look forward to working with you!

New problem solver

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63 Messages

2 m ago

just confirming this. see my reply to "/59 prefix delegation block changed" for details. Please post if anybody is getting any worthwhile support to fix this (not just from the Comcast_* bots).

Contributor

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13 Messages

2 m ago

I'll give you some more info which may be helpful. My modem was changed from the BWG (DPC3941B) to the CBR-T (CGA4131COM), my /56 IPv6 block remained the same. However, when IPv6 PD worked on my BWG (for about a year) the first /59 assignment was e0. A /56 contains 8 /59s, so e0 would be the 7th out of 8 of this block, the 1st is used by the BWG. Not sure how it came up with this but it remained the same for the time I had the BWG. Now with the CBR-T, the 1st /59 is for the modem and then it will PD the next /59 blocks so I get 20, 40... etc. I think it is a difference in how the firmware in the modem does PD. Unfortunately, I doesn't seem like there is currently a way in the CBR-T to "statically" bind these /59 PD to the downstream device.

(edited)

Recognized Contributor

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30 Messages

2 m ago

@Jason609 :  This is my exact problem.  There are a few of us in the thread I started on /59 changing.  I also had a "later" /59 assigned for quite some time & all of a sudden it changed back to the first one & broke routing.  Feel free to join us in the "/59 prefix delegation block changed" thread if you'd like.

New problem solver

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8 Messages

2 m ago

I can report the same issue here, also with the DPC3941B, unfortunately with no solution yet.

Official Employee

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16 Messages

Hello, @amessina, thank you for reaching out in our forum for help with your firmware and connectivity issues. I'd love to take a look at your account and work towards a fix. In order to get started can you please send me a private message using our new Peer-2-Peer feature? There's a chat bubble in the right-hand corner that will allow us to do so. 

Contributor

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21 Messages

2 m ago

I'm glad to see the community getting some traction better understanding these connectivity issues.  I hope they'll be resolved for real someday.  It's 2021 after all and IPv6 really should just work out of the box.

As for me, I've booked an installation appointment for AT&T Business Fiber.  The service offers Static IPs, officially claims to support IPv6 with prefix delegation, costs a bit less than Comcast, offers faster speeds, and is available on a month-to-month basis.  I'm wary of trading one set of problems for another but I'm cautiously optimistic.

Good luck everyone!

New problem solver

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8 Messages

1 m ago

@Comcast_Marcos, your handle doesn't pop up in the folks I can Peer-To-Peer with, though there is a @Comcast_Marc.

Official Employee

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15 Messages

@amessina Thanks for trying! So it shouldn't be one of our handles. Please search for just Comcast_Business. That is the handle that will be able to reach us privately. 

Recognized Contributor

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30 Messages

1 m ago

@amessina : Try to send a private message to "Comcast Business" and that will get the right person in touch with you.

New Contributor

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8 Messages

1 m ago

I also have a DPC3941B and am experiencing this - IPv6 PD works at reboot but then it stops routing IPv6 traffic after ~8-12 hours. Further, the web interface to interact with the modem is never responsive, even right after reboot. Connections to port 80 time out. Started a few days ago. Can't confirm whether it's correlated with a firmware update since the user interface is not reachable.

New problem solver

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63 Messages

1 m ago

@sfsmcipv6 similar to my experience. Looks like having my modem replaced fixed the issue for now (stable IPv6 for 24 hrs now). The prefix is still "random" on reboot, but clearing the DUID a couple times will eventually lead to the old prefix. 

I believe the modem I had was a "Cisco" modem (vertical modem, 4 ethernet ports) and they replace it with a "Technicolor" modem (horizontal, 8 ethernet ports)

New Contributor

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8 Messages

1 m ago

@flybynight thanks for your reply. your technicolor is working with prefix delegation? do you have static IPv4 IPs? from reading other posts on this forum I it seemed like the technicolor modem was still broken with prefix delegation.

New problem solver

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63 Messages

1 m ago

I do have a static /29 for IPv4. So far, IPv6 works just like it worked with the old modem prior to the firmware upgrade. I get a "random" /59 out of the static /56 assigned to the modem. But now, once I got that /59, it appears to remain the same as long as my DUID doesn't change. So certainly an improvement.

New problem solver

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63 Messages

1 m ago

Looks like there may be different "Technicolor" modems. Mine is the CGA4131 with 8 Ethernet and 8 Voice ports. It is a horizontal modem (just a bit too tall for 1U ;-) ).

Official Employee

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137 Messages

Thanks so much for reaching out to us with your concern. I can absolutely assist you with this. All I need is your full name, account number (follow link https://comca.st/3qwjKf5, account number is at the top right)and address including city, state, and zip code exactly how it reflects on the bill? Thanks in advance. -Rob K.