@williamjjames65_518880897646817 More experimentation leads to success! Toggling the client option Hardware Decoding First to off led to a restart and a warning that a update package for DirectX was needed. Good instructions for this, Reolink! I guess that my non-existent hardware decoder was tried first and then the software approach failed silently - not so good, Reolink!

@joseph_1979 I have the Reolink client installed on both Windows 11 and Windows 10 machines. While it seems fine using Clear on W11, the W10 machine shows no video in Clear but is fine with Balanced or Fluent. I've just discovered the Microsoft HEVC Extensions but installing that makes no difference. Does the Reolink client need something else, or reinstalling?