Thanks.
While it does work, it’s a rather round-about way to achieve what should be a very simple task. The private groups plugin is overkill for my use-case.
Anyway, it works.
Thanks @robin-w,
Nice to see that your plugin is being updated.
Is there a default group that all users are added to? The particular forum that I want to restrict is one that everyone must be able to see and have access to. Having to manually add every new user to the right group wouldn’t work.