Good news: Sonic.net supports "6in4" IPv6 tunnel.
Bad news: Pace 4111N-030 does not.
Good news: Able to replace RG with ZTE ADSL2+ modem and ASUS router.
Bad news: ASUS "6in4" IPv6 tunnel support doesn't support IPv6 prefix length greater than 64.
Good news: Hurricane Electric tunnel works.
Bad news: Sonic.net tunnel does not.
I am reasonably convinced this is because the IPv6 tunnel endpoints are:
• HE server: 2001:470:1f04:448::1/64
• HE client: 2001:470:1f04:448::2/64
• Sonic.net server: 2001:5a8:0:1::149e/127
• Sonic.net client: 2001:5a8:0:1::149f/127
ASUS RT-AC66U accepts the local client /64, but not the local client /127. So it automatically knows the HE server to be 2001:470:1f04:448::1, but thinks the Sonic.net server to be 2001:5a8:0:1::1 (as opposed to 2001:5a8:0:1::149e).
So I still can't create a Sonic.net "6in4" tunnel, but I can create an HE "6in4"tunnel. This is progress from a couple of years ago. BTW, ASUS RT-AC66U does offer a "6rd" option; so when ever Sonic.net gets a
Round Tuit, I guess I'll be good to go.
