Max: Yes it's now redirecting from https:/www.mudcat.org to https://mudcat.org for me. It wasn't when I posted - I checked.

However it's not redirecting from http://www.mudcat.org which gives a 404. That's what the OP got.

I don't know whether you intend http://mudcat.org to redirect to https://mudcat.org but it doesn't. I can get to http://mudcat.org by downgrading my browser's security settings. The OP probably has an old browser which does not automatically upgrade http to https.

It doesn't help that many browsers no longer display the www in the address bar. (One way to find out which you're using is the copy the address as if making a link.)

[And to users of my Mudcat Browser Tools addon: I added the redirects to the addon a couple of weeks ago, so you cannot actually get to http://mudcat.org.]