Joined: 01 Dec 2021 Posts: 289 Location: Maryland, United States
Posted: Sat Dec 04, 2021 1:41 Post subject: [SOLVED] WAN IPv6 Disabled
Several months ago my ISP (Comcast) switched to vCMTS (in my area) and since then with my Netgear R6300v1 router with the original Netgear firmware cannot maintain IPv6 for more than an hour or two. With the DD-WRT firmware the router cannot even recognize IPv6 from the WAN (on the System Information page it states WAN IPv6 - disabled). I am using dd-wrt.v24-47720_NEWD-2_K3.x_giga-R6300 firmware. If I connect my computer directly to the cable modem it recognizes IPv6. I have tried Native IPv6 from ISP and DHCPv6 with Prefix Delegation without any success. Once on a reboot of the router (without changing any settings) I was able to get WAN IPv6 and my computer recognized the IPv6 from the router. After many other reboots I was never able to duplicate it.
Any suggestions?
Last edited by PaulGo on Sat Apr 23, 2022 17:40; edited 2 times in total
Sounds like DD-WRT IPv6 default settings is not working for you; therefore DD-WRT requires a custom setup unless someone in this forum is using the same ISP you should get some help or use the DD-WRT Form Search to look for answers. The other option talk to your ISP Support or go to the ISP Forum for answers.
Another thing I've read on the forum that Enabling QoS breaks IPv6, not sure if it's build related. _________________ Home Network on Telus 1Gb PureFibre - 10GbE Copper Backbone
2x R7800 - Gateway & WiFi & 3xWireGuard - DDWRT r53562 Std k4.9
Off Site 1
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Joined: 01 Dec 2021 Posts: 289 Location: Maryland, United States
Posted: Sat Dec 04, 2021 17:00 Post subject:
Currently very few Comcast customers are on vCMTS and probably most of those who are on it don't know about IPv6. Comcast states Netgear is working on a firmware solution for currently supported routers. I have done searches and tried recommended solutions to get dd-wrt to recognize IPv6 on the WAN but none has worked. I do not have QoS implemented.
Since Comcast is a major ISP in the United States and soon will be implementing vCMTS throughout the US. Probably other cable systems will follow. So IPv6 WAN connection may become a major problem for users of dd-wrt.
IPv6 is not as "user friendly" in my opinion... I assume that you are using all of the default settings in DD-WRT for IPv6? How long do you wait to see if your router gets an IPv6 address? (sometimes there are large delays... like 24hrs for initial config)
Joined: 01 Dec 2021 Posts: 289 Location: Maryland, United States
Posted: Sat Dec 04, 2021 17:45 Post subject:
With vCMTS the lease renewal period is two hours. When I had CMTS several months ago before I tried dd-wrt the lease renewal period was two days. As I previously had mentioned with the original Netgear firmware IPv6 would be recognized on a reboot but lose IPv6 after an hour or two so I assume it was related to the lease renewal. Since I have been trying different thing I have not had the R6300 connected without a reboot for more than several hours. I will try a longer period.
Joined: 01 Dec 2021 Posts: 289 Location: Maryland, United States
Posted: Mon Dec 06, 2021 0:16 Post subject:
Wildlion,
I am a true novice with DD-WRT since I only installed it a few days ago.
Based upon my understanding of your instructions I did the first part of your instruction about Dhcp6 and Dhcp6c. I made sure the following was implemented:
dhcp6s: enable
sequential IPs: enable
Radvd: enable
I then saved and rebooted the router. I still have no WAN IPv6.
Under Administration - Commands I entered
ping6 -c 5 ff02::1%eth0
ping6 -c 5 ff02::1%br0
but I did not get any results.
Comcast (my ISP) does not have any information on how to implement IPv6. Also, in my area they have implemented vCMTS which is very new so it is unlike many other parts of the country.
Last edited by PaulGo on Mon Dec 06, 2021 2:07; edited 1 time in total
Joined: 08 May 2018 Posts: 14126 Location: Texas, USA
Posted: Mon Dec 06, 2021 2:52 Post subject:
I somehow figured it was a rhetorical question. I have a feeling that vCTMS is irrelevant; I don't think they changed how they have IPv6 configured by going virtual. If that is the case, then there's a lot of how-to's out there for other network gateway solutions that are wrong. And all of them I have read pretty much uses the same settings as DD-WRT default for IPv6... but I have also seen a few posts about how their IPv6 is not working... _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
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Linux User #377467 counter.li.org / linuxcounter.net
Joined: 01 Dec 2021 Posts: 289 Location: Maryland, United States
Posted: Mon Dec 06, 2021 15:44 Post subject:
This is why I believe it is related to Comcast's implementation of vCMTS. With the original Netgear provided firmware (latest available version) before vCMTS was implemented I was able to connect and stay connected to IPv6. After the implementation of vCMTS several months ago I could connect to IPv6 after a reboot but lose IPv6 after an hour or two (vCMTS changed the lease time from two days to two hours). With the original Netgear firmware after the implementation of vCMTS without a reboot I first had to use 6 to 4 tunnel to get a LAN IPv6 address and then running DHCP to get a WAN IPv6 address. Again, IPv6 would only be maintained for an hour or two.
Joined: 08 May 2018 Posts: 14126 Location: Texas, USA
Posted: Mon Dec 06, 2021 16:45 Post subject:
Well, there are only two things at play here : Comcast's IPv6 / vCTMS situation and (likely) what dhcp6 / IPv6 implementations are in the stock firmware or DD-WRT. Configuration issue or Comcast is b0rked. This is why I think that reserving all the code blocks when TCP/IP went public was a bad idea. Because now we have to deal with the haphazardly implemented IPv6 and CGNAT.
I would have to check configs and base code and verify what is being used in DD-WRT for dhcp client and server for IPv6; last I knew, I believe it was the code in the first link:
Perhaps it's time to review some things in the name of functionality and/or code reduction. IRT Wide-DHCP6 (first link), I tracked down the following information:
We literally cannot use the ISC dhcp client and server, etc. in embedded linux IRT custom firmware due to code size; I don't know exactly what the stock firmware is using, but I do recall seeing it in Linksys E-series device code tarballs in the past. _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
Contribute To DD-WRT Pogo - A minimal level of ability is expected and needed... DD-WRT Releases 2023 (PolitePol)
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Linux User #377467 counter.li.org / linuxcounter.net
If the windows 10 machine gets an IPv6 address, than the router should be no different because it should be acting like a client the same way... DD-WRT's ipv6 stack is not broken... it is that we are misunderstanding the posters usage or setup... I know Comcast sucks... but they should be able to provide some usage or they provide hardware which people are to use (and thus we have to reverse engineer). I know there are posts of people with IPv6 on pfsense with comcast
If you are on your dd-wrt router do you have an IPv6 local address?
If you got no response using either of those commands that means that somethign is not connected correctly... IPv6 depends heavily on pings and if neither side is responding to pings because those are local discovery pings that unless they are being dropped (bad practice). Not to say that you cannot do bad practice, but it makes it harder (I have done this in some network labs to prove points)
I am a true novice with DD-WRT since I only installed it a few days ago.
Based upon my understanding of your instructions I did the first part of your instruction about Dhcp6 and Dhcp6c. I made sure the following was implemented:
dhcp6s: enable
sequential IPs: enable
Radvd: enable
I then saved and rebooted the router. I still have no WAN IPv6.
Under Administration - Commands I entered
ping6 -c 5 ff02::1%eth0
ping6 -c 5 ff02::1%br0
but I did not get any results.
Comcast (my ISP) does not have any information on how to implement IPv6. Also, in my area they have implemented vCMTS which is very new so it is unlike many other parts of the country.
You might need to do this commands under the command line... and they should have been done one at a time... since the web-interpreter will think it is one command and not two ... so it probably errored out.