No password to type with a remote: the TV shows a code, you approve it on your phone.
Open Usherr. A TV’s own browser starts on Sign in with your phone; anywhere else, choose it on the sign-in page.
The TV shows a code like ABCD-EFGH and a QR code. The code works once, for five minutes.
Scan the QR code with your phone’s camera. Your phone has to be signed in to Usherr already. Or open Usherr on your phone, add /tv-code to its address, and type the code.
The phone shows the code and the kind of TV that asked (Chrome on NVIDIA Shield, say). Check the TV shows the same code, then press Approve. The TV signs in as you.
The phone warns you when the TV isn’t on your home network. Only approve a TV you can see in front of you, and never a code someone sent you.
The TV is listed under Signed-in devices (You, Your settings, Security in Broadcast; Settings, Security in Classic or Neu), where you can sign it out.
An administrator can switch it on or off under Server, People, Ways to sign in (in Classic or Neu: Settings, Account & Access, Ways to sign in). It’s on to begin with.