Highly recommend cupping your favourite coffee with different kinds of water (e.g. tap, mineral, DIY water see below). It's pretty eye opening.
Here's how to make your own, if you're motivated to try: https://www.baristahustle.com/diy-water-recipes-the-world-in-two-bottles/
Had similar behaviour last night. Turned out UnboundDNS had crashed in my opnsense firewall and took "internet connectivity" with it. Restarting the service fixed it in one click after I found it.