Likely causes:

• Windows using cached sign-in and refusing without network; switch to a local sign-in temporarily.
• Adapter disabled or in airplane mode.
• Router DHCP hiccups; renew IP or reboot the router.
• Captive portal on guest Wi-Fi blocking access.
• Date/time drift breaking SSL and logins.

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What it might be (likely causes)

• Microsoft account sign‑in needs a network
  When Windows thinks you must re‑authenticate a Microsoft account, it can block login if there’s no internet or SSL fails. A temporary local account login can get you in to fix networking.