I have my Craft 3 database on a separate server than my Craft webserver (load balancing) and when I use the download database backup function in Craft 3, it doesn't know where to look.
I haven't worked with a setup with separate locations for the DB and the site before so it's something new for me to work with.
From this answer, I think it's where I'd setup a custom backupCommand config, but I don't know where to start.
It's on an nginx setup if that helps?
Cheers.