10.1 PTR Realms are currently offline for hardware maintenance with a new build likely coming later today or tomorrow.

Patch 10.1 went offline, but it is not due to a weekly build. Instead, Blizzard clarified servers have been taken down for server hardware maintenance. We should see them go back this afternoon at the latest (or evening for us in Europe) with a new build hopefully arriving as well or tomorrow.

(Source)

Greetings!

Our 10.1 PTR Realms will be going offline at 2pm PDT (5pm EDT) for some server hardware maintenance (unrelated to a new weekly build, although we’re working on that too).

This will be an extended maintenance and may go into tomorrow; either way we expect the PTR Realms to be back online by tomorrow afternoon at the latest.

Thanks!