Strange issue: UPNP and IPv6

[neil0311]

The short story...I had no issues with IPv6 until I swapped my Comcast rented SB6120 for a Technicolor TC8305C gateway. I did this to remove an old DOCSIS 2.0 emta used only for voice. One device seemed simpler than two.

I am using a RT-AC68P (and have a RT-N66U). The AC68P is running Merlin build 376.48_1. After lots of attention from Comcast, and posts on their forum and DSL Reports, it looks like I've isolated my IPv6 issue to the following:

UPNP enabled on the router = IPv6 works
UPNP disabled on the router = IPv6 does NOT work

UPNP has always been disabled. I've tried various firmware versions (and both routers) over the last month (including the Zoidberg alpha) with UPNP disabled, and IPv6 has been hosed. When I enabled (actually did it by accident when resetting), it suddenly worked. Toggling it on/off can reproduce the ability/inability to get IPv6 working.

The Comcast folks swear it has nothing to do with them and is all about a bug somewhere in the router firmware. Any thoughts? Any wild guesses?

 

[neil0311]

No one? Two routers (AC68P and N66U) running a static configurations and all of a sudden require UPNP to get a v6 address and Comcast swears it's the router?

My guess is the Comcast supplied gateway (TC8305C) but they swear it can't be. Just want to know if anyone has ever heard of anything even remotely close with any version of Asus or Merlin firmware. I can reproduce this at will.

UPNP on = IPv6
UPNP off = No IPv6

v6 settings:

Native with DHCP-PD
Stateless
Connect to DHCP Server automatically = Enable
Enable Router Advertisement.= Enable
Enable DHCPv6 Server = Enable

 

[greg50]

Have you tried the new alpha firmware with the new IPv6 engine?

 

[neil0311]

Have you tried the new alpha firmware with the new IPv6 engine?

Yes, but not since I discovered this connection with upnp. I tried it when it was first posted and v6 was not working. Not clear whether or not it would have worked with upnp enabled or not.

 

[RogerSC]

I always have UPnP disabled, and have IPv6 enabled, and everything's fine, including IPv6. As you can see from my signature file, I'm using the Zoidberg 49_alpha2 release as well.

Comcast is my ISP, and I use DHCP6-PD (prefix delegation) mode. All good at the moment.

 

[neil0311]

I always have UPnP disabled, and have IPv6 enabled, and everything's fine, including IPv6. As you can see from my signature file, I'm using the Zoidberg 49_alpha2 release as well.

Comcast is my ISP, and I use DHCP6-PD (prefix delegation) mode. All good at the moment.

Thanks. That's why this is so weird. I've always had upnp disabled and would prefer to keep it that way.

The Comcast folks claim they've reviewed their side of things and swear the issue is on the CPE side. I'll upgrade to 376.49 when Merlin releases it and once again do a full/hard reset and see if it fixes the issue. It's just hard to understand how a router with no issues and a static configuration suddenly stops getting a v6address and it's the router's issue?

Oh well. It's obvious no one here has seen this before.

 

[greg50]

It can also be the Technicolor's fault. Is it possible to test it with a different HGW? It's out btw, give it a go.

 

[neil0311]

It can also be the Technicolor's fault. Is it possible to test it with a different HGW? It's out btw, give it a go.

Ah, just noticed .49 is released. The next step would be swapping out the gateway if the issue persists after a router reset and firmware update.

 

[RogerSC]

Flashed 49_0 last night, and IPv6 is working fine with UPnP disabled this morning. All good so far. Since you're having a problem, I'd suggest being sure to reset to factory defaults after flashing, and manually re-enter your settings. Just to be sure that things are normalized before checking out the new firmware.

 

[RMerlin]

Also review the System Log for any unusual error occuring when you disable it. I can't think of any technical reason as to why one would interfere with the other, especially since I don't even enable the IPv6-specific functionality in miniupnpd.