UDM IPV6 stopped working after upgrade or engineering works

Hi.

I have a UDM on latest firmware 1.10.4 and controller 6.0.54. Since I got the router in Jan 2020 I have had IPV6 working no problem with the DHCPV6 settings on the WAN set to /56 and then using prefix delegation on the WAN.

I recently upgraded from a 150MBPs service to 500MBPs. I believe IPV6 was working still but not sure. There was also some engineering works done whilst I was away from my home last week and I believe after this IPV6 just stopped working on my line. I tried factory resets and downgrading firmware on the UDM but no joy.

I have a Nokia router provided as part of the upgrade to 500MBPs and this is working fine and is giving me the IPV6 prefix in the GUI.

Has anyone else seen similar or have any troubleshooting steps/any way to use static IP setup on the UDM? Not having IPV6 is very anoying.

Thanks.
Andrew.

I had the same thing!! 150 -> 500, and this broke IPv6 on my Mikrotik router; it wouldn't get a /56 allocated.
Then, one day, it would again!

I think someone at Hyperoptic's network team broke something, and more recently fixed it!