IPv6 works on the router but doesn’t work on LAN devices

j2bv16 · February 22, 2024, 3:16pm

My network looks like this: ISP - modem - Openwrt router - LAN devices

Before I switched to openwrt, I used tp-link which worked flawlessly. After switching to openwrt I can't use IPv6.

I tried many things to make it work. I've set relay mode on WAN6 and LAN. After doing that, my devices get ipv6 addresses but I can't use them.

If I ping the IPv6 address from the router it goes ok.
When i test if IPV6 on https://test-ipv6.com/ it's says I'm not using the protocol.

My ISP is Claro Dominican Republic. Modem provided works fine

mk24 · February 22, 2024, 5:22pm

The first step is to find out what type of IPv6 service you have. Using a default configuration where wan6 is only proto dhcpv6 with no options will usually discover this. You need to know if the ISP offers a prefix and what size it is.

Also make sure your modem is operating in "bridge" or "passthrough" mode instead of as a "gateway" The gateway mode does routing inside the modem and it may limit the LAN side to /128s as would be expected if it were only endpoints and not routers.

j2bv16 · February 22, 2024, 6:34pm

This is the info i have on LuCi

mk24 · February 22, 2024, 6:37pm

Yes your ISP device issued only a /128, so you cannot route it further. This is not good. If this is all that you can get that means you'll have to NAT6 the LAN into it the same as you would with a single IPv4.

Alpha1096 · February 22, 2024, 6:38pm

Believe me, I've been through this for so many hours. The reason this doesn't work because the default gateway is not being distributed through the lan clients. If you go to network places and view the ethernet or wifi adaptor ip address, you'll notice the missing gateway.

I feel like something is wrong with how routes are set in relay mode.

You can try this in the mean time, it's actually suggested by someone and it fixed the issue for me.

Edit /etc/config/network file and put this under wan6 interface.
option ip6prefix 'aaa:bbb:ccc:ddd::/64'

Where aaa:bbb:ccc:ddd is your first 64bits wan6 address.

In your case it is 2001:1308:a599:bc00

So put this line.
option ip6prefix '2001:1308:a599:bc00::/64'

I maybe wrong about the prefix 64 as all this is kind of new to me.

Lan all to relay mode and wan6 also all to relay mode.
After adding the above line , be sure to restart interface. And hopefully it would work.

mk24 · February 22, 2024, 7:29pm

Relay mode requires a /64 routed to the WAN interface. The upstream's assignment of a 128 means the OP does not have that. The ISP box is treating the OpenWrt router as a single endpoint.

NPeca75 · February 22, 2024, 8:54pm

Hi

well, it will be good to know what IPv6 addresses tp-link served to your PC
do you have some notes from your old setup? maybe you remember test-ipv6.com result ?

main question is
did tp-link magically grabbed some PD from WAN ?
or tp-link hide whole LAN behind one /128 and serving ULAs to your LAN ?

j2bv16 · February 22, 2024, 11:28pm

This the modem data on ipv6, if that helps

j2bv16 · February 22, 2024, 11:39pm

This did not work

j2bv16 · February 23, 2024, 12:12am

More testing on the wifi provided by the modem, i get a different IP on every device.

j2bv16 · February 23, 2024, 12:57am

Ok. I disabled "prefix delegate type" option on the ISP modem, added the DNS server 3 and for some reason everything is working

Alpha1096 · February 23, 2024, 2:05am

Something is not right? Clearly his isp router is set to receive /56, how come he's only getting 128.

Alpha1096 · February 23, 2024, 2:39am

share output of ifstatus wan6.

or

share output of all. This will help the community better understand.

> uci export network; uci export dhcp; uci export firewall; \
> head -n -0 /etc/firewall.user; \
> ip -6 addr ; ip -6 ro li tab all ; ip -6 ru; \
> ls -l  /etc/resolv.* /tmp/resolv.* /tmp/resolv.*/* ; head -n -0 /etc/resolv.* /tmp/resolv.* /tmp/resolv.*/* ; ifstatus wan6

You may hide mac addresses.

j2bv16 · February 23, 2024, 11:01am

ifstatus WAN6
{
"up": true,
"pending": false,
"available": true,
"autostart": true,
"dynamic": false,
"uptime": 31799,
"l3_device": "eth0.2",
"proto": "dhcpv6",
"device": "eth0.2",
"metric": 0,
"dns_metric": 0,
"delegation": true,
"ipv4-address": [

],
"ipv6-address": [
	{
		"address": "2001:1308:a599:bc00:ea48:b8ff:fe4d:a77a",
		"mask": 64,
		"preferred": 56222,
		"valid": 56222
	}
],
"ipv6-prefix": [
	{
		"address": "2001:1308:a599:bc00::",
		"mask": 64,
		"class": "WAN6",
		"assigned": {
			
		}
	}
],
"ipv6-prefix-assignment": [
	
],
"route": [
	{
		"target": "2001:1308:a599:bc00::",
		"mask": 64,
		"nexthop": "::",
		"metric": 256,
		"valid": 56222,
		"source": "::/0"
	},
	{
		"target": "::",
		"mask": 0,
		"nexthop": "fe80::1",
		"metric": 512,
		"valid": 1777,
		"source": "2001:1308:a599:bc00:ea48:b8ff:fe4d:a77a/64"
	}
],
"dns-server": [
	"2606:4700:4700::1111",
	"2606:4700:4700::1001",
	"2001:4860:4860::8888",
	"fe80::1"
],
"dns-search": [
	
],
"neighbors": [
	
],
"inactive": {
	"ipv4-address": [
		
	],
	"ipv6-address": [
		
	],
	"route": [
		
	],
	"dns-server": [
		
	],
	"dns-search": [
		
	],
	"neighbors": [
		
	]
},
"data": {
	"passthru": "00170030260647004700000000000000000011112606470047000000000000000000100120014860486000000000000000008888"
}

}

Alpha1096 · February 23, 2024, 2:01pm

So ... You can try now without my fix. See if you're getting PD now. Remove the line i told you to add in network file then restart interface. If you're still able to access internet over ipv6 then good otherwise re-add the line.

Atleast we will know how it works.

j2bv16 · February 23, 2024, 2:27pm

Its working well with your line added. Will test removing it later

fakemanhk · February 23, 2024, 8:52pm

Because some ISP will provide only a prefix, for example my ISP is exactly doing the same as OP, which gives /56 prefix without address, so in this case WAN6 doesn't need an address, the most important thing: /56 prefix already there, and the /128 WAN address is just a by-product of using DHCPv6. In fact OP doesn't really need to add "ip6prefix" line in this case due to the presence of RA.

suppenkasper0815 · June 14, 2025, 2:48pm


BusyBox v1.31.1 () built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 OpenWrt SFE, r15568-b3eccbca7c
 -----------------------------------------------------
root@ArcherD50:~# ifstatus wwan6
{
        "up": true,
        "pending": false,
        "available": true,
        "autostart": true,
        "dynamic": false,
        "uptime": 8726,
        "l3_device": "wlan0",
        "proto": "dhcpv6",
        "device": "wlan0",
        "metric": 0,
        "dns_metric": 0,
        "delegation": true,
        "ipv4-address": [

        ],
        "ipv6-address": [
                {
                        "address": "2a04:ec82:5:d101:d66e:ef
f:fea1:c4dd",
                        "mask": 128,
                        "preferred": 2075,
                        "valid": 5675
                }
        ],
        "ipv6-prefix": [
                {
                        "address": "2a04:ec82:5:d1f8::",
                        "mask": 62,
                        "preferred": 2075,
                        "valid": 5675,
                        "class": "wwan6",
                        "assigned": {

                        }
                }
        ],
        "ipv6-prefix-assignment": [

        ],
        "route": [
                {
                        "target": "2a04:ec82:5:d101::",
                        "mask": 64,
                        "nexthop": "::",
                        "metric": 256,
                        "valid": 2068,
                        "source": "::/0"
                },
                {
                        "target": "2a04:ec82:5:d100::",
                        "mask": 56,
                        "nexthop": "fe80::3a10:d5ff:fe85:d8c
c",
                        "metric": 512,
                        "valid": 1399,
                        "source": "2a04:ec82:5:d1f8::/62"
                },
                {
                        "target": "2a04:ec82:5:d100::",
                        "mask": 56,
                        "nexthop": "fe80::3a10:d5ff:fe85:d8c
c",
                        "metric": 512,
                        "valid": 1399,
                        "source": "2a04:ec82:5:d101:d66e:eff
:fea1:c4dd/128"
                },
                {
                        "target": "::",
                        "mask": 0,
                        "nexthop": "fe80::3a10:d5ff:fe85:d8c
c",
                        "metric": 512,
                        "valid": 1399,
                        "source": "2a04:ec82:5:d1f8::/62"
                },
                {
                        "target": "::",
                        "mask": 0,
                        "nexthop": "fe80::3a10:d5ff:fe85:d8c
c",
                        "metric": 512,
                        "valid": 1399,
                        "source": "2a04:ec82:5:d101:d66e:eff
:fea1:c4dd/128"
                }
        ],
        "dns-server": [
                "fd00::3a10:d5ff:fe85:d8cc",
                "2a04:ec82:5:d101:3a10:d5ff:fe85:d8cc"
        ],
        "dns-search": [

        ],
        "neighbors": [

        ],
        "inactive": {
                "ipv4-address": [

                ],
                "ipv6-address": [

                ],
                "route": [

                ],
                "dns-server": [

                ],
                "dns-search": [

                ],
                "neighbors": [

                ]
        },
        "data": {
                "passthru": "0038001400010010fd0000000000000
03a10d5fffe85d8cc00170020fd000000000000003a10d5fffe85d8cc2a0
4ec820005d1013a10d5fffe85d8cc005600102a04ec820005d1013a10d5f
ffe85d8cc"
        }
}
root@ArcherD50:~# ping6 google
ping6: bad address 'google'
root@ArcherD50:~# ping6 google.de
PING google.de (2a00:1450:4001:829::2003): 56 data bytes
64 bytes from 2a00:1450:4001:829::2003: seq=0 ttl=117 time=1
4.309 ms
64 bytes from 2a00:1450:4001:829::2003: seq=1 ttl=117 time=1
2.713 ms
64 bytes from 2a00:1450:4001:829::2003: seq=2 ttl=117 time=1
3.484 ms
64 bytes from 2a00:1450:4001:829::2003: seq=3 ttl=117 time=1
1.711 ms
64 bytes from 2a00:1450:4001:829::2003: seq=4 ttl=117 time=1
2.164 ms
64 bytes from 2a00:1450:4001:829::2003: seq=5 ttl=117 time=1
2.476 ms
64 bytes from 2a00:1450:4001:829::2003: seq=6 ttl=117 time=1
2.857 ms
64 bytes from 2a00:1450:4001:829::2003: seq=7 ttl=117 time=1
2.197 ms
64 bytes from 2a00:1450:4001:829::2003: seq=8 ttl=117 time=1
1.258 ms
64 bytes from 2a00:1450:4001:829::2003: seq=9 ttl=117 time=1
0.901 ms
^@64 bytes from 2a00:1450:4001:829::2003: seq=10 ttl=117 tim
e=10.932 ms
c64 bytes from 2a00:1450:4001:829::2003: seq=11 ttl=117 time
=10.777 ms
64 bytes from 2a00:1450:4001:829::2003: seq=12 ttl=117 time=
11.213 ms
^C
--- google.de ping statistics ---
13 packets transmitted, 13 packets received, 0% packet loss
round-trip min/avg/max = 10.777/12.076/14.309 ms
root@ArcherD50:~#
Die Verbindung wurde getrennt.

Hey guys,

I just wanna extend my Fritzbox Network which has an Dual Stack Light Internet Connection.

When I connect directly to my Fritzbox it's both working fine with my smartphone.

When I connect to my openwrt router I get the same IPv6 on my device. I can ping directly to the internet from the openwrt router which is configured as a relay as described here

Ipv6 with relayd wireless extender

Update:

I found that the problem has something to do with a wrong gateway. How can I change it to the dns address which is my Fritzbox ipv6 and also the ipv6 gateway.

There is a wrong fe80 in the beginning instead of fd00

Protocol: DHCPv6 client
Prefix Delegated: 2a04:ec82:5:d1fc::/62
Address: 2a04:ec82:5:d101:c0e:76ff:fe6d:d024/128
Gateway: fe80::3a10:d5ff:fe85:d8cc
DNS 1: fd00::3a10:d5ff:fe85:d8cc
DNS 2: 2a04:ec82:5:d101:3a10:d5ff:fe85:d8cc

lleachii · June 15, 2025, 11:35am

@psherman

Can we split this post into a new thread?

suppenkasper0815 · June 16, 2025, 2:03pm

Of course, I just don't know how and I think it's the same issue and everybody is suffering with ipv6 things, especially if you just want a dump AP and it seems like unrealistic to use it one day proper...

Unbelievable that any 9€ China Repeater has less stress and trouble than our big advanced brave openwrt gadgets....

The article above is not working.

I tried the same thing now with serveal devices. It's all the same issue.

I think it has the wrong gateway.

I also just noticed from external networks I can't reach my openwrt devices via ipv6.

So I guess it's still the problem with a wrong gateway. I already wrote the gateway into the device properties, but no chance...

So maybe someone which is able to use ipv6 in extender mode can share a how to that works... I would appreciate it