Not getting an ipv6 address with Merlin on a RT-AC5300

[Nitin]

Was using the older asus rt-ac3200 and was getting ipv6. Switched to a asus rt-ac5300, no ipv6 no matter what I do.

Comcast tells me that everything is "enabled" on their end for the cable modem to be handing out ipv6. The cable modem is a arris sb6183.

Any pointers?

 

[L&LD]

Did you turn off all network equipment (including modem) for at least 10 minutes and preferably closer to the half to one hour mark?

 

[Nitin]

I switched out the cable modem with a new one (same model) and replaced the router with an upgraded model. Should those two actions not constitute a full "recycle" as far as the systems at "hq" are concerned?

 

[thelonelycoder]

Did you try to wire your computer directly to the modem to see if you get an IPv6 adddress assigned?
This will tell you if the modem does in fact do it.
Make sure you have IPv6 enabled in the interface settings.

 

[Nitin]

Yes, when connected direct to the modem, I do get an ipv6 address.

 

[thelonelycoder]

Yes, when connected direct to the modem, I do get an ipv6 address.

Good, that gives us a better basis to troubleshoot the issue.

There are 5 Settings available for IPv6, depending on what service your ISP Provides.
If unsure, start with native and if you don't get an IPv6 IP, work your way down the list.

 

[Nitin]

"Native" was the one that worked on the AC3200 but I've now tried all of the options on the list, no luck.

I've also now tried the "official" ASUS firmware for this router to remove the Merlin firmware as a variable. No luck.

IMO, it's clearly a firmware issue cause when connected directly to the cable modem all devices get an IPv6 address immediately (I tried a different laptop also).

Also, found this in the system logs:
Aug 27 12:11:34 dnsmasq[9671]: bad IPv6 address at line 23 of /etc/dnsmasq.conf
Aug 27 12:11:34 dnsmasq[9671]: FAILED to start up

Sad panda

 

[john9527]

Also, found this in the system logs:
Aug 27 12:11:34 dnsmasq[9671]: bad IPv6 address at line 23 of /etc/dnsmasq.conf

telnet/ssh to the router and append the output of the following

cat /etc/dnsmasq.conf

 

[Nitin]

telnet/ssh to the router and append the output of the following

cat /etc/dnsmasq.conf

Here you go... there's no line 23! https://gist.github.com/gniting/ae5983c322a2ca33ccfdb324bc2ef41d (Pasting as a gist cause if I paste the file as-is, it triggers some random cloudflare security flag and it disallows me to post).

 

[Deleted member 22229]

Was using the older ac3200 and was getting ipv6. Switched to a sc5300, no ipv6. Comcast tells me that everything is "enabled" on their end for the cable modem to be handing out ipv6. The cable modem is a arris sb6183.

Any pointers?

I have the exact same issue with my 3100 using Merlin and stock firmware it will not obtain a IPv6 address no matter what i do. I have tried two different modems same issue. Directly connected to the computer all works fine no problem.

I ended up putting my N66U back in the line using Johns latest fork and IPv6 works great every time. Go back to the 3100 no dice no IPv6. Not sure what's going on wether Comcast changed something or Asus broke something. Strange indeed.

 

[Nitin]

I have the exact same issue with my 3100 using Merlin and stock firmware it will not obtain a IPv6 address no matter what i do. I have tried two different modems same issue. Directly connected to the computer all works fine no problem.

I ended up putting my N66U back in the line using Johns latest fork and IPv6 works great every time. Go back to the 3100 no dice no IPv6. Not sure what's going on wether Comcast changed something or Asus broke something. Strange indeed.

"John's latest fork...", educate me a bit on this? Maybe a link?

 

[ColinTaylor]

"John's latest fork...", educate me a bit on this? Maybe a link?

http://www.snbforums.com/threads/fork-update-for-374-43-available-v18e3.18914/

But the AC5300 is not supported.

 

[john9527]

Here you go... there's no line 23!

The last line of dnsmasq.conf that you posted is the last thing to be autogenerated by the firmware. Do you have a dnsmasq.conf.add or a dnsmasq.postconf?

 

[Nitin]

The last line of dnsmasq.conf that you posted is the last thing to be autogenerated by the firmware. Do you have a dnsmasq.conf.add or a dnsmasq.postconf?

Nope, no such files present in /etc/
Here's a screenshot.

 

[john9527]

Nope, no such files present in /etc/

These would be custom files that you had generated, one of the following

/jffs/configs/dnsmasq.conf
/jffs/configs/dnsmasq.conf.add
/jffs/scripts/dnsmasq.postconf

 

[Nitin]

These would be custom files that you had generated, one of the following

/jffs/configs/dnsmasq.conf
/jffs/configs/dnsmasq.conf.add
/jffs/scripts/dnsmasq.postconf

Both those directories are empty. I searched everywhere for files named "dnsmasq*". Results are in the attached screenshot.

 

[ColinTaylor]

Try opening /etc/dnsmasq.conf in "vi" and seeing if you get an error, like "incomplete last line" or there are garbage characters somewhere.

Do the same for:
/tmp/resolv.conf
/tmp/resolv.dnsmasq
/etc/dnssec-trust-anchors
hosts.dnsmasq <-- also in the /etc directory

(For some reason cloudflare blocks /e t c /h o s t s.d n s m a s q)

 

[Nitin]

Try opening /etc/dnsmasq.conf in "vi" and seeing if you get an error, like "incomplete last line" or there are garbage characters somewhere.

Do the same for:
/tmp/resolv.conf
/tmp/resolv.dnsmasq
/etc/dnssec-trust-anchors
hosts.dnsmasq <-- also in the /etc directory

(For some reason cloudflare blocks /e t c /h o s t s.d n s m a s q)

Opened all of those files in vi but did not get any warning. When I "cat" the files on command line, there's no funny chars at the end of line either.

/tmp/resolv.dnsmasq and /e t c/hosts.dnsmasq are empty.

 

[ColinTaylor]

Seems to be the same problem as this: http://www.snbforums.com/threads/solved-ipv6-on-378-55_0-kills-dhcp.27743/

 

[john9527]

Seems to be the same problem as this: http://www.snbforums.com/threads/solved-ipv6-on-378-55_0-kills-dhcp.27743/

Good catch!

So the answer for @Nitin is to remove the entries from the LAN pages for DNS servers (you should leave these blank anyway except for special cases). If you are trying to use custom DNS servers, enter them on the WAN page.