IPv6 MTU Problem, perhaps related to PPP

[PabloAbonia]

Hi, I am currently using using Merlin's 376.45 on an RT-AC56U, and have been banging my head around an IPV6 instability. The problem is that traceroute works on my computers, but rarely if ever works on the router. It always fails on the very first hop from router->cable modem when run on the router, but works sporadically from other devices.

Efforts at reducing the WAN MTU in web interface alone, radvd.conf alone, or both all fail, with pings having a new ceiling, while the traceroutes continue to fail.

I finally allowed the default dnsmasq.conf to load, and noticed the PPP1* interfaces were added to it, whereas I had only allowed the br0 interface in my custom dnsmasq.conf (see my current broken one below)

As such, I am wondering if DSL related MTU changes, are sitting on top of my cable modem MTU in way that I can not fix.

Other than this, Merlin's firmware has worked quite well and has allowed me to customize my lan to my liking which is very much appreciated.

Thanks for any thoughts,

Pablo

pid-file=/var/run/dnsmasq.pid
user=nobody
resolv-file=/tmp/resolv.conf
servers-file=/tmp/resolv.dnsmasq
no-poll
min-port=4096
bind-dynamic
interface=br0
interface=ppp1*
no-dhcp-interface=ppp1*
domain=fakename.lan
expand-hosts
bogus-priv
local=/fakename.lan/
no-negcache
cache-size=1500
dhcp-range=lan,192.168.1.100,192.168.1.150,255.255.255.0,86400s
dhcp-option=lan,3,192.168.1.1
dhcp-option=lan,15,fakename.lan
dhcp-option=lan,44,192.168.1.1
dhcp-option=lan,252,"\n"
dhcp-lease-max=253
dhcp-authoritative
read-ethers
addn-hosts=/etc/hosts.dnsmasq
quiet-dhcp
server=/apple.com/209.18.47.61
server=/apple.com/209.18.47.62

 

[PabloAbonia]

Update. Whatever is going wrong with IPV6 it appears to be specific to "Native IPV6" alone.

I gave up on Native, and proceeded to use a tunneling service that I had used in the past. That is working flawlessly whereas any attempt to use native failed repeatedly several times within minutes.

Also, I would like to agree that whatever the problem with native is, it occurs at the very first hop which I'm assuming is the modem, and not the internet side device the modem is connected to.


Pablo