I have a version 1 apple tv which only plays audio in screen mirroring from a streaming service

I have a version 1 apple tv which only plays audio in screen mirroring from a streaming service

If you are doing AirPlay screen mirroring, then the Apple TV box is at least 2nd generation.

Please re-examine your exact model. Identify your Apple TV model - Apple Support

is this a problem due to the age of the unit

Yes, that is likely. Several content providers have requirements for newer models. See their support websites for details.

E.g.:

- Netflix doesn’t support AirPlay screen mirroring with any model device.

- Apple TV+ requires Apple TV (3rd generation or later).

- HBO Max requires an AirPlay 2-compatible device (i.e. 4th generation or later).

- Disney+ requires Apple TV (3rd generation or later) for AirPlay.

- Some services differentiate for mirroring between iOS apps (accepted) and web browser (not accepted).