Sky+ Won't connect to Three Mobile Broadband anymore, FAIL/FAIL

[miloshcanary]

A few days ago Sky+ Broadband connection stopped working.  Happens occassionally, so tried usual steps to restart sky (mains power off/on), restarting router etc... But nothing working.

Tried both Wifi and LAN cable to the router, but always comes up FAIL/FAIL

All other devices are connecting via WIFI or LAN cable fine.

Connecting Sky+ to my phone (EE) hotspot does connect propertly.

Have spent morning talking to three, but they are convinced it's a sky problem.  Cannot find any contact number/details for sky, so hoping posting on here could help.

Is there some special router config needed to get Sky+ HD to work? DNS or other setting?

Router is  Zyxel 5G router, NR5103E

[miloshcanary]

After googling more on the three forums, found a lot of people were having issues with IPv6.  Seems like three recently enabled this, and sky+ box does not support this (at least not with current config).  At least reading online that's what others have said.

If you google just three words, can find much better hits on the issue:
ipv6 sky three

The link I found that helped me was here:
https://community.three.co.uk/t5/Broadband/FYI-IPv6-Prevented-VPN-Connection/m-p/14851#U14851

For me, connected sky to router via lan cable (was still fail/fail), then logged onto the Zyxel NR5103E)
Network Settings -> Home Networking -> Lan Setup

Find option

LAN IPv6 Mode Setup : Disable


Also Changed NDS Values
Static:
Use Googles Ips:
8.8.8.8
8.8.4.4

Saved, restarted the hub, and sky is finally connected via LAN!