Is that a HDHomerun Prime tuner?
If so, MC can take a little while to "find" a network tuner such as that. Have you tried waiting a couple of minutes to see if it reappears?
Also, if this has started happening in MC22 as well as MC23 now, then that would point to something changing in your environment or setup. Change router? Installed other software that uses a tuner?
Have you tried letting the PC sleep instead of turning it off?