Troubleshooting 4via6 connectivity

I have 2 nodes connected to Tailscale:

  1. Subnet router to my home network / “Router” (not an actual router, just a VM that has access to all the services I’d like to access from Client through Router)
  2. My personal computer / “Client”

For testing purposes they are currently on the same local network, but I expect that should not create issues on it’s own.

I followed the subnet router docs and since the range of my local network would otherwise be conflicting I was also happy to find docs mapping them through ipv6.

I picked a random ID=56:

❯ tailscale debug via 56

and reconfigured my Router and Client:

# Router
sudo tailscale up --advertise-routes=fd7a:115c:a1e0:b1a:0:38:c0a8:100/120
# Client
sudo tailscale up --accept-routes

Then enabled the subnet routes in the web GUI.

Now, I would expect to be able to ping, but not actually able to

ping6 fd7a:115c:a1e0:b1a:0:c8:c0a8:1c8
# no answer
❯ host
Host not found: 3(NXDOMAIN)

What else can I do to troubleshoot this?
Have I correctly understood the concept what “4via6” is supposed to do?