Thank you everyone who commented! Got it solved by reseting the Networks.
Settings > Network & Internet > Network Reset > Reboot PC

Additional info:

I already tried resetting the store using this guide .

Done trying to re-register using this guide

Tried the built-in troubleshooter in the settings, to no avail.

Still...

Hi TenForums,

I'm having a problem opening Microsoft Store, it keeps telling me to check my internet connection. Even though I have good connection. It wont let me open apps downloaded from the...