No Site Options

I’ve just installed this plug-in – whose documentation/installation instructions qualify as cryptic at best – and at length figured out that to test its features I’d need to add the define to the wp-config first.

At that point only, “Sites” appeared in the Dashboard menu. I get an Add New Site options page with a blank input for the title, a selection dropdown for transport type, and a category selection menu – and that’s it: Nothing else for adding site url or for saving choices once made. If I do select the alternative transport type – WordPress.com REST – I instantly get a 500 error, while the site is saved (I guess by an Ajax process).

I don’t know if there is a decent explanation for what’s going wrong. Maybe the sites I wish to connect – on WP 4.9.5 – will prove unworkable with this plug-in, but I did try turning off all other plugins and switching to Twenty Seventeen. At this point, I’m tempted to leave a 1-star review and warn people away.