Multisite configuration issues

Hi there, I'm getting a weird issue on my multisite that I've been struggling with for a while. When I type in the url of my site without 'www', it gets re-directed to: http://www.domain.net/wp-signup.php?new=domain.net (note the no https). I have https enabled for all my subdomains and mapped domains.

I've seen some similar issues on here but never any clear solutions. I've done all the de-activate plugins, themes process, cleared caches, etc. so please don't recommend that lol.

I have the standard network setup rules in my htaccess file. Any help would be much appreciated. Thank you.