Setting up IPv6 on a RT-AC68U

[gee]

Hello,

I've tried a few times but never managed to get IPv6 working on my RT-AC68U with Merlin wrt.
I am running on latest from July, I think have correct settings but I only get a link-local IP for my computer...
When I plug my computer directly in the ISP's outlet I do get a global IPv6 so I'm guessing the computer's configuration is fine.

My ISP is CondoInternet/WaveG.

Here are the (default) settings:
Basic Config
Connection type Native
DHCP-PD Enable

IPv6 LAN Setting
LAN IPv6 Address
LAN Prefix Length
LAN IPv6 Prefix
Auto Configuration Stateless
Lease time 86400

IPv6 DNS Setting
Connect to DNS Server automatically Enable

Auto Configuration Setting
Enable Router Advertisement Enable
Enable DHCPv6 Server Enable

I tried changing them but it did not seem to change anything.

This is what I can see in IPv6 logs:
IPv6 Connection Type Native with DHCP-PD
WAN IPv6 Address 2604:4080:115f:0:XXXX:XXXX:XXXX:XXX/64
WAN IPv6 Gateway fe80::XXX:XXXX:XXXX:1800
LAN IPv6 Address /0
LAN IPv6 Link-Local Address fe80::XXXX:XXXX:XXXX:9e30/64
DHCP-PD Enabled
LAN IPv6 Prefix /0
DNS Address


Is the /0 ok for LAN?

From merlinwrt I can ping IPv6 so the router is getting its connection fine (though I don't always see the IPv6 address in the logs as above... but I can always ping... not sure if it's a bug or not). My computer getting only a link-local IPv6 can't ping or connect to anything (v6 related, but v4 works fine).

I've looked at various other threads on the subject, but never found something that helped.

What am I missing?
Thanks!

 

[gee]

Pretty please?

 

[kvic]

I believe LAN IPv6 Prefix /0 is no good. You want /64. A bit more info from this thread.

 

[gee]

I was afraid of that.
I looked at that other thread, but what do you mean by "Enter /64 prefix (that you set in Speedport in the previous step) in LAN IPv6 Address." ?
I tried pasting the IPv6 I see in the logs there (without the /64 prefix) and now my computer gets a global IPv6, but it's really similar to the link local one (meaning it uses the mac address to fill it, maybe it's ok?) and I still can't ping the outside world with it...

Thanks!

 

[kvic]

See if below works for you:

Basic Config
Connection type Native
DHCP-PD disable

IPv6 LAN Setting
LAN IPv6 Address 2604:4080:115f:0::/64
LAN Prefix Length 64
LAN IPv6 Prefix
Auto Configuration Stateless
Lease time 86400
​

 

[gee]

I couldn't put the address in as you typed it: "2604:4080:115f:0::/64", so I tried without the "/64" part and it accepted, but the result is pretty much the same as above.
I get the same IPv6, can ping the IPv6 of the router but not further... I tried with my android phone in case, but it's the same.

 

[kvic]

Perhaps read emails from your ISP carefully...did they assign you any other ipv6 address other than the one we see above?

Hmm..running out of ideas. Sorry..

 

[gee]

That's a fair question. I will ask them tomorrow, thank you!

 

[gee]

So I called and am a little surprised... I pretty much got nothing out of that call...
I was asked to get to Asus latest as there was an IPv6 fix in it, which I did but it didn't change anything. I was pretty much told to use default settings and that they didn't know more than that...

With default settings nothing happened, like before, using your (kvic's) settings gives me an IPv6, and after verification without the router, it's the correct IPv6 my computer would get from my ISP (I currently have that computer directly plugged to the ISP, no router in between).

So I'm not sure where the issues lies...
- The computer plugged directly is fine, so it seems that the computer's config is fine, but maybe with the router in between it's not the same behavior?
- The router gets it correct IPv6 and can ping the outside world, and be pinged by the local network...
but I can't get both of them :/

 

[john9527]

What operating system on your computer?
Also, is there anything of interest in the router syslog?

 

[gee]

I am running on Arch Linux.
As for syslog, I don't know really what would be of interest so I'm not sure.
I guess apart from "start_nat_rules: apply the nat_rules(/tmp/nat_rules_vlan2_vlan2)!" it seems fine (I just don't know if those nat rules are the cause of my issue here, hence I noted that one in particular).

Thanks!

 

[john9527]

I am running on Arch Linux.

Are you by chance running ufw? I was just setting up Linux Mint on a laptop (Ubuntu based) and found that I had to add an allow rule for DHCPv6, port 546 UDP to get an address. Don't know if it's the same default setup for Arch.

For the syslog, see if any errors are posted by dnsmasq or dhcp6s.

 

[gee]

I don't think I'm using it (it's not installed), I have iptables installed but with an empty set of rules so it should be ok.
As for these 2, I don't see any errors, only "positive" lines.

In case it helps, here's the syslog routing table:

IPv6 routing table
Destination Next Hop Flags Metric Ref Use Iface
<PC_IPv6>/128 <PC_IPv6>:9077 UC 0 48 0 br0
2604:4080:115f::/64 :: U 256 0 0 br0
2604:4080:115f::/64 :: UA 256 2 0 vlan2
fe80::/64 :: U 256 0 0 vlan1
fe80::/64 :: U 256 0 0 eth1
fe80::/64 :: U 256 0 0 eth2
fe80::/64 :: U 256 0 0 br0
::/0 fe80::211:bcff:fe9c:1800 (the WAN Gateway) UGDA 1024 864 0 vlan2
2604:4080:115f::/128 :: U 0 17 1 lo
2604:4080:115f:0:<ROUTER_IPv6>/128 :: U 0 76 1 lo
fe80::/128 :: U 0 0 1 lo
fe80::/128 :: U 0 0 1 lo
fe80::/128 :: U 0 0 1 lo
fe80::/128 :: U 0 0 1 lo
<ROUTER_LINKLOCAL>/128 :: U 0 16 1 lo
<ROUTER_LINKLOCAL>/128 :: U 0 0 1 lo
<ROUTER_LINKLOCAL>/128 :: U 0 46 1 lo
<ROUTER_LINKLOCAL>/128 :: U 0 0 1 lo
ff02::1/128 ff02::1 UC 0 1 0 vlan2
ff02::2/128 ff02::2 UC 0 1 0 vlan2
ff02::1:2/128 ff02::1:2 UC 0 1 0 vlan2
ff02::1:ff00:7265/128 ff02::1:ff00:7265 UC 0 2 0 vlan2
ff02::1:ff7f:2774/128 ff02::1:ff7f:2774 UC 0 1 0 vlan2
ff02::1:ffe8:935e/128 ff02::1:ffe8:935e UC 0 6 0 vlan2
ff02::1:fff8:9077/128 ff02::1:fff8:9077 UC 0 12 0 vlan2
ff00::/8 :: U 256 0 0 eth0
ff00::/8 :: U 256 0 0 aux0
ff00::/8 :: U 256 0 0 vlan2
ff00::/8 :: U 256 0 0 vlan1
ff00::/8 :: U 256 0 0 eth1
ff00::/8 :: U 256 0 0 eth2
ff00::/8 :: U 256 0 0 br0

 

[tarassippo]

Hello,

I've just found this old thread which explains the same problem I am experiencing and was wondering if anyone found the solution.

My RT-AC68U is connected to my ISP modem/router (which doesn't support bridge mode), and I have attached a screenshot of my WAN configuration



Now, if I connect my laptop to the ISP router directly, I get an IPv6 address - this a test on ipv6-test.com



But, when I connect my laptop to the Asus router and I do the test, I can see I don't get the IPv6 address:



This is my current IPv6 settings



But I have tried several different combinations and no luck.

Any suggestions would be much appreciated.

Tia.

 

[gee]

Tia.

Unfortunately I haven't found anything good on that topic.
I'm currently on my 2nd 68u router, so it was not the unit, unless it's a serie issue...

I've also tried running dd-wrt instead of asuswrt (with or without merlin's) and it is no better on that topic.

The router itself does get a good IPv6, and ping6 works from it, so I'd guess that the issue is in the DHCP/delegation.. but why do others with the same router have no issue? Is it a revision thing? I believe I'm on revision A if it matters.

 

[tarassippo]

Update: I've just changed the settings on the Asus router to 'passthrough' and there you go my laptop has got now the IPv6

 

[gee]

What do you mean by passthrough?

Do you have other equipment connect to the router that also get ipv6?

 

[tarassippo]

Well, the ISP modem is the one who 'deals with' the Internet connection, so its' the one who gets all the external IPs...

 

[tarassippo]

This is the setting in the Asus router

 

[gee]

Hmmm, I'm afraid your passthrough may just give the IPv6 address to the first connected computer instead of taking one and giving others to the local network. Well that's what I guess from the word passthrough. If that's the case, it's not a really helpful thing.