Cannot access store or realms

My Minecraft installation on my desktop cannot find the Store, Realms, my friends worlds, or the Servers list. It's completely offline. My internet connection is good (for instance, I'm filling out this ticket from the same computer).

My phone and laptop can connect to the Store, all using the same internet connection, so this is not an issue with my overall connection. I have tried completely disabling the windows firewall and Avast, with no change. I can't find anything in the Minecraft settings that would indicate an "offline" mode to toggle.