CDVR logs this message
2026/08/18 06:00:01.820483 [ERR] Failed to start stream on channel 5.1 via 10924759: HDHomeRun: All Tuners In Use
despite immediately following with opening a connection to another tuner and recording succesfully.
Were all the tuners on the first HDHomeRun in use when it fell over the the second one? That would be normal.
You may need to web into the HDHomeRun to see the actual tuner status.
Remember that the tuner priority is setup so it will try all available tuners in your first source before falling back to the other options in the source list. If you have 2 HDHR, you could put one in for priority for recording in the server, and then in the clients, have the other be the top priority for when you are watching live TV I believe.
In the end, channels manages all of that behind the scenes, so as long as it gets where it needs to go, I wouldn't worry about the message in the log.