RT-AC5300 IPv6 Stops Working and IPv6 DNS Setting

[Rumline]

Running Merlin 380.68_4 on an RT-Ac5300. Enabling IPv6 works fine for a while. Then after several hours the IPv6 interface on the RT-AC5300 stops working. No response to IPv6 ping and of course no DNS. Have to reboot the router to re-gain IPv6 connectivity.

Also, I've set the manual IPv6 DNS servers to Google's but the DHCPv6 still hands the RT-AC5300's internal IPv6 interface as the only IPv6 DNS server. I've got "Advertise router's IP in addition to user-specified DNS" set to "No" and don't see this behavior on the DHCPv4 server.

I have static public IP's for both IPv4 (/31) and IPv6 (/56) from Comcast Business.

Any advise for either/both of these issues?

Thanks.

 

[e38BimmerFN]

What is the Mfr and model of the ISP modem?
Does ASUS OEM FW exhibit that same issues?

 

[Rumline]

Netgear CG3000DCR
HW Version: 1.04
Firmware Version: V3.01.15
Operating Mode: Residential Gateway


Yes, the same behavior occurred with the stock ASUS firmware. It's the reason I moved over to Merlin.

Thanks.

 

[e38BimmerFN]

is the ISP modem/router bridged? If not you might bridge the modem or use the DMZ for the ASUS router. Having two routers on the same line can cuase problems. I would try this first.

If your seeing this on both OEM and Merlin, then the problem may be with your ISP modem router first off.

If the bridging or DMZ still doesn't work, then the core issue maybe with the IPv6 core package that comes from ASUS GPL which RMerlin gets from ASUS. However, lets see if bridging or DMZ on the Netgear modem/router will show something better.

Netgear CG3000DCR
HW Version: 1.04
Firmware Version: V3.01.15
Operating Mode: Residential Gateway


Yes, the same behavior occurred with the stock ASUS firmware. It's the reason I moved over to Merlin.

Thanks.

 

[Rumline]

I now have the Netgear ISP modem in bridged mode. I also updated to Merlin 380.69. I have the static IPv6 WAN setup and can move traffic from the ASUS over eth0.

admin@RT-AC5300-54A0:/tmp/home/root# nslookup www.google.com 2001:4860:4860::8888
Server: 2001:4860:4860::8888
Address 1: 2001:4860:4860::8888 google-public-dns-a.google.com

Name: www.google.com
Address 1: 2607:f8b0:400f:806::2004 den16s03-in-x04.1e100.net
Address 2: 172.217.2.4 den16s03-in-f4.1e100.net


admin@RT-AC5300-54A0:/tmp/home/root# ping -6 www.google.com
PING www.google.com (2607:f8b0:4000:80b::2004): 56 data bytes
64 bytes from 2607:f8b0:4000:80b::2004: seq=0 ttl=54 time=22.543 ms
64 bytes from 2607:f8b0:4000:80b::2004: seq=1 ttl=54 time=22.458 ms
64 bytes from 2607:f8b0:4000:80b::2004: seq=2 ttl=54 time=45.314 ms
64 bytes from 2607:f8b0:4000:80b::2004: seq=3 ttl=54 time=22.356 ms

I am having trouble with the IPv6 LAN settings now that I am in Static IPv6 mode on the ASUS. Nothing I try seems to work. If my public static IPv6 is 2603:xxxx:yyyy:zzzz::/56. I tried 2603:xxxx:yyyy:zzzz::1/64 for LAN and I also tried a private range fd38:88cc:ba6f:7220::/64 and fd38:88cc:ba6f:7220::/56. Nothing moves over IPv6 from the LAN side to the internet.

What is the ASUS expecting for the LAN side IPv6 configuration?

Thanks.

 

[Rumline]

Update. Switching the ASUS back to Native IPv6 mode made the LAN to WAN traffic start working. If the WAN IP address is 2603:xxxx:yyyy:8600::/56 the LAN IP address becomes 2603:xxxx:yyyy:86f0::1/60. That's what comes up when in native mode. But when I switch back to Static mode and use the 2603:xxxx:yyyy:86f0::1/60 for LAN, IPv6 traffic to the internet stops working.

Same question: If in IPv6 WAN Static mode, what should be entered for IPv6 LAN on the ASUS?

I'm not sure I trust the upstream Comcast DHCPv6 that's handing the ASUS an IP address. It could be I'm losing IPv6 when the lease expires.

Thanks.

 

[e38BimmerFN]

Sounds like you first might contact your ISP to see what exact IPv6 mode you should be in for this to work. Seems like you need Dynamtic or Auto as it works there and not use Static. I would talk to them first to make sure you have the right modes. If there only supporting Dyn or Auto, then I presume you can't use Static. Just like on IPv4. If ISPs only support Dynamic or Auto, Static can't be used.

I now have the Netgear ISP modem in bridged mode. I also updated to Merlin 380.69. I have the static IPv6 WAN setup and can move traffic from the ASUS over eth0.

admin@RT-AC5300-54A0:/tmp/home/root# nslookup www.google.com 2001:4860:4860::8888
Server: 2001:4860:4860::8888
Address 1: 2001:4860:4860::8888 google-public-dns-a.google.com

Name: www.google.com
Address 1: 2607:f8b0:400f:806::2004 den16s03-in-x04.1e100.net
Address 2: 172.217.2.4 den16s03-in-f4.1e100.net


admin@RT-AC5300-54A0:/tmp/home/root# ping -6 www.google.com
PING www.google.com (2607:f8b0:4000:80b::2004): 56 data bytes
64 bytes from 2607:f8b0:4000:80b::2004: seq=0 ttl=54 time=22.543 ms
64 bytes from 2607:f8b0:4000:80b::2004: seq=1 ttl=54 time=22.458 ms
64 bytes from 2607:f8b0:4000:80b::2004: seq=2 ttl=54 time=45.314 ms
64 bytes from 2607:f8b0:4000:80b::2004: seq=3 ttl=54 time=22.356 ms

I am having trouble with the IPv6 LAN settings now that I am in Static IPv6 mode on the ASUS. Nothing I try seems to work. If my public static IPv6 is 2603:xxxx:yyyy:zzzz::/56. I tried 2603:xxxx:yyyy:zzzz::1/64 for LAN and I also tried a private range fd38:88cc:ba6f:7220::/64 and fd38:88cc:ba6f:7220::/56. Nothing moves over IPv6 from the LAN side to the internet.

What is the ASUS expecting for the LAN side IPv6 configuration?

Thanks.