I've just found an odd issue with Let's Encrypt... I have domain.co.uk setup, with Let's Encrypt SSL, and it was working fine. I then added beta.domain.co.uk, with Let's Encrypt SSL, and it made domain.co.uk redirect to beta.domain.co.uk, causing a redirect loop. Both had 'Auto-Subdomain' set to 'None'. Any ideas what could be causing this please? I'll try and do more testing, but I'm a bit reluctant because it's not a site I want to be offline.