Unusual behaviour on my PC. Access to all Microsoft services blocked.

One Drive does not connect. Microsoft.com loads on Chrome & Firefox but the link to the Microsoft account login page is dead. Outlook.com does not load at all. Connect to VPN (same country) and access to all Microsoft services reappears. Disconnect from VPN, connect to mobile hotspot (different ISP) and problem appears again. Reinstalled windows and problem persists. Wiped HDD and installed Linux and the unusual behaviour continues on Firefox and Chromium. Weird! All other devices on broadband and mobile internet are behaving normally. Any ideas? Curse? Nation-State?