YouTube livestreams wouldn't play - fix was disabling IPv6 on router

TL;DR: livestreams broken but regular videos fine = try turning off IPv6 on your router before you factory reset.

Symptoms: livestreams stuck in an endless buffering loop, on-demand videos played fine, every other device in the house worked, fast internet.

Tried everything: cache/data clear, full power cycle, lowering quality to 480p, OS updates, Google DNS. Nothing worked.

The fix: disabled IPv6 on my router, power cycled the stick, livestreams instantly worked.

The cause: my ISP’s IPv6 path was broken. Other devices fall back to IPv4 instantly so they look fine, but Fire OS keeps trying the dead IPv6 route. Live segments need constant delivery, so livestreams break while regular videos survive.