IPV6 Instability in 380.57

[billyzs]

EDIT: apparently CTF is incompatible with IPV6 tunnels. Disabling CTF fixed the problem.

I've been happily using a HE IPV6 tunnel on my AC56 running 378.56_2 to circumvent GFW for a while. After updating to 380.57 I've noticed that once in a couple hours, my Windows 10 client would report that IPV6 internet connectivity had been lost entirely, while the tunnel is still updated with the correct IPV4 IP address (I've double checked to make sure); rebooting the router seems to fix the issue. Does anyone else have the same problem? I've attached the log file. Would really appreciate any help and more than willing to provide more specific debugging information if someone can tell me where to investigate into. Thanks.

 

[Nullity]

I've been happily using a HE IPV6 tunnel on my AC56 running 378.56_2 to circumvent GFW for a while. After updating to 380.57 I've noticed that once in a couple hours, my Windows 10 client would report that IPV6 internet connectivity had been lost entirely, while the tunnel is still updated with the correct IPV4 IP address (I've double checked to make sure); rebooting the router seems to fix the issue. Does anyone else have the same problem? I've attached the log file. Would really appreciate any help and more than willing to provide more specific debugging information if someone can tell me where to investigate into. Thanks.

Are you sure this is caused by the router and not the DPI of the GFW?

 

[billyzs]

Are you sure this is caused by the router and not the DPI of the GFW?

I'm not sure, but rebooting fixes the issue and it wasn't present in the previous version of the firmware. Also clients are seeing an IPV6 interface with not internet connectivity, rather than a working tunnel w/ discarded packets or whatever GFW does to mess things up, so I'm leaning towards the router.

But then again it's my hypothesis, haven't figured out a way to test this.

 

[Nullity]

But then again it's my hypothesis, haven't figured out a way to test this.

Understood.

Perhaps a packet sniffer like tcpdump or wireshark would be useful? Wireshark has a color-coordinated GUI that exposes errors in a reasonably easy way to understand.

 

[pilotboy72]

I saw something similar on my Ac3200 and AC5300 with occasional loss of Internet access and even to other devices on my network using IPV6. Disabling IPV6 restored connectivity for both Internet and local devices but obviously isn't a long-term fix.

I'll do some packet capture runs this weekend and see what I find. I'm glad to hear I'm not the only one seeing this.

 

[billyzs]

Well shame on me. A simple Google search turned this up: http://www.snbforums.com/threads/ipv6-tunnel-instability-with-378-51-on-rt-n66u.23553/

CTF might be the culprit. I have it disabled for now, will see if it actually fixes the issue.

 

[Nullity]

Well shame on me. A simple Google search turned this up: http://www.snbforums.com/threads/ipv6-tunnel-instability-with-378-51-on-rt-n66u.23553/

CTF might be the culprit. I have it disabled for now, will see if it actually fixes the issue.

I have no experience with IPV6, but I know that the packet sniffing abilities of tcpdump are limited (tcpdump crashes) when CTF is enabled.

Maybe related?

 

[billyzs]

Left CTF disabled for about 40 hours and pinged Google's IPV6 address every two minutes during this time. haven't had any complete loss of IPv6 internet access apart from a few occasional dropped packets.