I gave their protocol page a look; it’s extremely in-depth. I have no idea what a vector clock is but now I get to learn. I like how they explain why blockchain isn’t a good fit.
I’m a touch worried about the extensability of the protocol, but I haven’t given it a deep read yet. I very much appreciate the share!
The VPN catches all network traffic and puts it far away - you can’t be on vpn and see local network resources (casting targets) at the same time.
If your vpn has an app, check your settings for something like “local network access”.
Otherwise, start reading about split-tunnels and/or default gateways