IPv6 not working on Archer C50

Ea128 · May 9, 2021, 12:05pm

Hello guys,Hope You all Are Doing Great !

Recently i got a Tp-link archer C50 and i flashed it with openwrt v19.07.7.I have connected it to my ISP router via a lan cable.

The WAN6 interface on the second router seems to be working as it gets a good IPv6 address and ping6 google.com (from the router) works. But the LAN interface is getting an address and the clients connected to it have no IPv6 internet connectivity.

uci show dhcp.lan


dhcp.lan=dhcp
dhcp.lan.interface='lan'
dhcp.lan.start='100'
dhcp.lan.limit='150'
dhcp.lan.leasetime='12h'
dhcp.lan.dhcpv6='server'
dhcp.lan.ra='server'
dhcp.lan.ra_management='1'

ifconfig

br-lan    Link encap:Ethernet  HWaddr 3C:84:6A:D1:77:4B
          inet addr:192.168.12.1  Bcast:192.168.12.255  Mask:255.255.255.0
          inet6 addr: 2001:1670:c:4787::1/64 Scope:Global
          inet6 addr: fd1e:106:18d6::1/60 Scope:Global
          inet6 addr: fe80::3e84:6aff:fed1:774b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1179 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1369 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:268746 (262.4 KiB)  TX bytes:996870 (973.5 KiB)

eth0      Link encap:Ethernet  HWaddr 3C:84:6A:D1:77:4B
          inet6 addr: fe80::3e84:6aff:fed1:774b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:52277 errors:0 dropped:0 overruns:0 frame:0
          TX packets:22927 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:60287716 (57.4 MiB)  TX bytes:4957326 (4.7 MiB)
          Interrupt:5

eth0.1    Link encap:Ethernet  HWaddr 3C:84:6A:D1:77:4B
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:40 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:3773 (3.6 KiB)

eth0.2    Link encap:Ethernet  HWaddr 3C:84:6A:D1:77:4C
          inet addr:192.168.100.71  Bcast:192.168.100.255  Mask:255.255.255.0
          inet6 addr: 2001:1670:c:4787::1/128 Scope:Global
          inet6 addr: 2001:1670:c:4787:3e84:6aff:fed1:774c/64 Scope:Global
          inet6 addr: fe80::3e84:6aff:fed1:774c/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:48649 errors:0 dropped:5 overruns:0 frame:0
          TX packets:19149 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:59176758 (56.4 MiB)  TX bytes:4406256 (4.2 MiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:305 errors:0 dropped:0 overruns:0 frame:0
          TX packets:305 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:31990 (31.2 KiB)  TX bytes:31990 (31.2 KiB)

wlan0     Link encap:Ethernet  HWaddr 3C:84:6A:D1:77:4B
          inet6 addr: fe80::3e84:6aff:fed1:774b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:24480 errors:0 dropped:0 overruns:0 frame:0
          TX packets:50618 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:5066810 (4.8 MiB)  TX bytes:62939928 (60.0 MiB)

ping -6 dns.google (From the Openwrt router via ssh)

PING dns.google (2001:4860:4860::8844): 56 data bytes
64 bytes from 2001:4860:4860::8844: seq=0 ttl=112 time=10.890 ms
64 bytes from 2001:4860:4860::8844: seq=1 ttl=112 time=43.605 ms
64 bytes from 2001:4860:4860::8844: seq=2 ttl=112 time=79.175 ms
64 bytes from 2001:4860:4860::8844: seq=3 ttl=112 time=10.815 ms
64 bytes from 2001:4860:4860::8844: seq=4 ttl=112 time=10.676 ms
64 bytes from 2001:4860:4860::8844: seq=5 ttl=112 time=10.064 ms
64 bytes from 2001:4860:4860::8844: seq=6 ttl=112 time=11.001 ms
64 bytes from 2001:4860:4860::8844: seq=7 ttl=112 time=33.986 ms
64 bytes from 2001:4860:4860::8844: seq=8 ttl=112 time=13.165 ms

i am using the default configs from out of the box.

Thanks In advanced !

mikma · May 9, 2021, 1:07pm

Check for prefix delegation (or DHCPv6-server) in the ISP router. Without a delegated (at least /64) prefix you can't use IPv6 in the LAN unless you use work-arounds such as the IPv6 relay mode.

Ea128 · May 9, 2021, 7:49pm

Let me explain again I have an isp provided router from where I get my internet now the router which they provided is basic so I have connected it to my openwrt box to get more advanced feature but the problem is that when I am connected to the isp router the ipv6 works perfectly fine whereas when I connect to the openwrt box the ipv6 doesn't work on the lan side of thing the openwrt box is able to ping ipv6 but when I am on its lan ipv6 doesn't work though I get a ipv6 address from the openwrt box on my lan devices .

Also I can't bridge as my isp is not giving me the ppoe username and password

Here is my isp router settings

Ea128 · May 9, 2021, 7:55pm

As you can see I am ble to ping ipv6 from openwrt

Ea128 · May 9, 2021, 7:55pm

But when I am on my pc I get this

(So sorry as my account is new I am not able to link image in one go)

vgaetera · May 10, 2021, 12:43am

Collect the diagnostics and post it to pastebin.com redacting the private parts:

uci show network; uci show dhcp; uci show firewall; ifstatus wan6; \
ip address show; ip route show table all; ip rule show; iptables-save -c

Ea128 · May 10, 2021, 7:01am

Here is the pastebin https://pastebin.com/CZN3Kpkq

LGA1150 · May 10, 2021, 8:32am

Your paragraph is hard to read without punctuations. Let me fix that:

Let me explain again: I have an isp provided router from where I get my internet now. The router which they provided is basic, so I have connected it to my openwrt box to get more advanced feature. But the problem is that when I am connected to the isp router, the ipv6 works perfectly fine, whereas when I connect to the openwrt box, the ipv6 doesn't work on the lan side of thing. The openwrt box is able to ping ipv6, but when I am on its lan ipv6 doesn't work though I get a ipv6 address from the openwrt box on my lan devices.

The root cause is your ISP router requires a prefix via DHCPv6-PD from your ISP, but does not allow LAN clients to require sub-prefixes from itself. In order to make OpenWrt's IPv6 routing work natively, OpenWrt needs at least a /64 prefix.

If nothing else is connected to your ISP router, consider setting it to bridge mode, and let OpenWrt handle the address assignment.

Ea128 · May 10, 2021, 9:02am

Thank for correcting my punctuation,but yeah I can't use bridge mode as my isp has not provided me with ppoe password I only have my username
So, isn't there any other way we can accomplish this ?

mikma · May 10, 2021, 9:21am

IPv6 Relay? https://openwrt.org/docs/guide-user/network/ipv6/start#ipv6_relay

Ea128 · May 10, 2021, 10:06am

But relaying won't make the openwrt box give ips right ?

LGA1150 · May 10, 2021, 10:29am

Does your provider at least allow you to reset the password?

Ea128 · May 10, 2021, 10:42am

Actually the thing is the settings get synced automatically from the isp some feature on the huawei ont which they provided to us so when I asked for a reset they were like ur router will be automatically synced

LGA1150 · May 10, 2021, 12:27pm

Have you asked for bridge mode?

Ea128 · May 10, 2021, 12:40pm

Actually I did call, but hotline representatives were clueless about what I was talking ! not kidding

LGA1150 · May 16, 2021, 1:40pm

Since you have the access to ISP router configuration, have you tried:
Unhiding the password in your browser's developer tools?
Backing up the configuration to a file (most Huawei ISP modems allow that) and decoding it?

Ea128 · May 16, 2021, 1:59pm

I don't know how it is done to be honest if I would know that then all my problems would be solved