I've finally solved the issue. By disabling "pref.vpn.disable.pause" I got outlook (and Reddit for some reason) working like a charm again.
Settings > Advanced > Low level settings > pref.vpn.disable.pause: disable
I've installed the Outlook app on my phone and had trouble setting up my mail (IMAP). After some random turning off and on actions I was able to setup the client. But then I noticed I wasn't able to send of receive mails. I've alsof tried a different mail client and was unable to setup my mail...