Renewing SSL cert - how to disable stud?


So I forgot to add my non-www domain to my SSL certificate.

So I’m trying to use LetsEncrypt’s certbot-auto tool to expand my existing SSL cert.

Unfortunately, when I run the tool, I get the following errors.

The program stud (process ID xxx) is already listening on TCP port │
│ 443. This will prevent us from binding to that port. Please stop the │
│ stud program temporarily and then try again.

I’ve run mup stop but it seems that doesn’t stop stud. How do I stop stud from running?