RT-AC68U stops providing ipv6 addresses to clients

[laptander]

Hello.
I am using ASUS RT AC68U router with Merlin's firmware 378.53. My main problem is that router suddenly stops providing ipv6 addresses to its clients.
The only way how can I enable it again is power off router for a long time, than turn it on again. Then IPv6 addresses are given by router to clients. However, some time later (it may be after 1 minute or even after 24 hours) it stops providing them.
I was thinking, that my ISP could cause problems, but then I find out, that it was wrong. I can connect to router via ssh (via IPv4, because it is always working) and successfully execute ping6 ipv6.google.com So, router itself has access to ipv6 internet.
I am glad to debug problem if you tell me how.

 

[jim769]

Dont really have a solution but rather a comment. I am using AC68R and Merlins 53 since its release and IPv6 has been stable and solid since the flash. Comcast is my ISP. You can try going into the router and disable and enable IPv6 again then reboot modem then router and see if that helps.

 

[bbunge]

This may seem like a broken record but check in Tools for the amount of free NVRAM.

 

[laptander]

I found another thread http://www.snbforums.com/threads/problem-with-ipv6.22253/ and I wanted to say that my problem was exactly duplicate in details: turned off firewall and static (means not via DHCP) setting of IPv6 address. Maybe this info could help troubleshooting.
What I did for now: I reset all settings to defaults, than set all needed thing back. Then rebooted. Now ipv6 addresses are given by router to clients. Do not know if it will break again, we will see...
By the way, maybe problem was that I did not restored defaults after flashing update? Or it does not matter?
For now NVRAM usage 40524 / 65536 bytes

Important notice. IPv6 settings are only applied and start working only after rebooting. Not just pressing Apply button. At least, for first time of setting IPv6 settings.
And another strange thing that I noticed: while setting ipv6 settings first time, if I set connection type to Native (just to see wat will happen, my ISP still do not run DHCPv6), then applying settings, router becomes unreachable at all (even via ipv4). So I need to do full reset again.

 

[jim769]

I always do a complete factory reset after any firmware flash even if they say it's not needed. And yes indeed after enabling v6 you would need a reboot to obtain a v6 address. Hope it works for you i have Native here so things may be a bit different for you.

 

[laptander]

I always do a complete factory reset after any firmware flash even if they say it's not needed.

Ok, but can you say if settings exports (.CFG binaries) are compatible between different firmware versions? Bacause it would be very annoying to manually configure all things after every update.

 

[L&LD]

Ok, but can you say if settings exports (.CFG binaries) are compatible between different firmware versions? Bacause it would be very annoying to manually configure all things after every update.

NOT compatible. A full manual and minimal configuration is recommended.

Of course, you can try john's utility http://www.snbforums.com/threads/user-nvram-save-restore-utility.19521/

 

[sdajkdcbhzb]

http://www.snbforums.com/threads/asuswrt-merlin-378-53-is-now-available.24172/#post-179821 Use this setting and set WAN DHCP query frequency to Normal Mode. Comcast's system for IPv6 is DoS'ing us :/

 

[jim769]

Comcast v6 i

http://www.snbforums.com/threads/asuswrt-merlin-378-53-is-now-available.24172/#post-179821 Use this setting and set WAN DHCP query frequency to Normal Mode. Comcast's system for IPv6 is DoS'ing us :/

It's not DOS'ing you it's just comcast has a known issue they refuse to address that allows the v6 neighbor table to overflow constantly and the router logs the event every time it happens. That code that Merlin posted is the work around for the issue and it stops the router from logging the event. That code was in Merlin's firmware by default until this latest build because others that dont have comcast were having some issues with it, so now comcast users have to enter the code them self by SSH/Telnet.

 

[Chrysalis]

on the new merlin firmware dnsmasq is responsible, on john's fork its radvd.

So those are the places to look.

 

[laptander]

What I did for now: I reset all settings to defaults, than set all needed thing back. Then rebooted. Now ipv6 addresses are given by router to clients. Do not know if it will break again, we will see...
By the way, maybe problem was that I did not restored defaults after flashing update? Or it does not matter?

Important notice. IPv6 settings are only applied and start working only after rebooting. Not just pressing Apply button. At least, for first time of setting IPv6 settings.

It happened again. IPv6 addresses disappeared. What I doing: I was playing with enabling and disabling firewall. Than applying changes. After I reboot router, addresses successfully appeared.
So, maybe problem is that after any changes to ipv6 I need rebooting?