After enabling the thing and did some basic setup, I noticed I can’t actually follow this from my own mastodon instance. Many hours of debugging later, I learned it’s a combination of bug in the plugin itself and the fact that I hacked my own networking to resolve my websites to a local IP. Mastodon and WordPress both have their own check to ensure no local IP being accessed so that needs to go. Fixing Mastodon side was easy but there’s no escape hatch for WordPress.
The solution is, well, make the domains resolve to “external” IP instead, add that IP alias to the router and then forward the request to the actual web server 🕺