Static internal IPv6 setup with dynamic PD

[sergiodj]

You need to assign one of the /64 from HE statically to your LAN as an additional virtual address. To be able to use that /64 for devices to access the Internet you need to set up a tunnel according to HE's documentation.

Alright, great.  I already have the GIF setup, so all that's left is to create a Virtual IP and attach it to the LAN.

But why did you do this in the first place? I though you wanted to use static ULAs in addition to your ISPs GUA. Now you got another set of GUAs - a whole /48 of them - from HE.

I initially planned to use static ULAs, but decided to move to static GUAs because I found that there are some idiosyncrasies with AdGuard Home.

My plan is to configure my AG with a static IPv6 from HE and use it internally as the IPv6 DNS server.

[zan]

I then manually set the IPv6 of that machine as static, and assigned an IP from the ULA I'd just created.  I can't make it connect to the internet via IPv6, but I guess that's expected because ULAs aren't supposed to be routable...?  If it's supposed to work, then I have to figure out the gateway to u

Your machine should have GUA if you want it to reach internet. Leave the network setting as it used to and configure an additional static ULA to the interface, consult its OS how to do it.
Also make sure that ULA is reachable from clients, you might want to setup a route to the ULA via link local or assign a helper ULA to OPNsense LAN interface.

I initially planned to use static ULAs, but decided to move to static GUAs because I found that there are some idiosyncrasies with AdGuard Home.

Let just focus on making it work from now on =)