Spent a few evenings troubleshooting why vDash couldn't recognise my connection to a 2021 Polestar2. Initially suspected the cheap DOE cable but dug in and ended up getting trace from Wireshark.
Side question, why does Wireshark and vDash running together just crash. This was a little tedious.

In the end I ruled out the cable and figured that my Tailscale (VPN tunnel) service was swallowing all the DoIP packets.

So the lesson to share is as follows. If you're trying to connect via DOE then do first check you don't have odd VPN stuff going on at all.
The specific tell that gave it away was
'Get-NetRoute -DestinationPrefix "169.254.0.0/16"' from an admin powershell. In error mode this returned multiple entries. Once I'd disabled tailscale it only returned one.

Hope this helps someone save a bit of debugging time.