Update: Contacted SiliconDust support. They had me turn on diagnostics. No idea what they saw but they are sending me a new unit.

Logs. Trying to tune to same channel from second device:

20250928-22:45:38 Tuner: tuner0 tuning 43.2 CBS-HD (8vsb:605MHz-2)
20250928-22:45:38 Tuner: tuner0 streaming http to 10.0.0.67:49324
20250928-22:46:06 Tuner: tuner1 tuning 43.2 CBS-HD (8vsb:605MHz-2)
20250928-22:46:16 HTTP: rejecting request ...

I just added a HDHomeRun FLEX DUO to my network. Working great, but will only work with one device at a time.

Test setup: HDHomeRun app on my iPhone, and 2 AppleTVs

Which ever one I open first, it will work perfectly.

If I try to open a channel on a second or third device, it just says "No ...