My bad. I didn't intend to conflate the two interfaces. My Z-Stick never failed, even though my Insteon MODEM did. I just assumed that it was just good luck and that the Z-Stick would fail on a subsequent reboot. I have very mixed feelings concerning my predominantly Insteon dual-band mesh deployment, although my years of signal problems seemed to be related to an intermittently failing Insteon 2413u MODEM, which worked just well enough out of the box to have me running around troubleshooting problems. My original 2413u ultimately failed last year and after replacing it with a new one, all my flakey connectivity problems vanished. The new one is really solid in every way, but appears to have much newer firmware.A vast majority of the reports of problems have been with the PowerLinc 2413U which uses the FTDI driver. Not many reports of new Z-Stick problems with High Sierra, although we seem to get a few USB problem across the board (all interfaces) with each new macOS release.
I bugged Matt and Jay for a while with a problem that appeared to be a signal-to-noise problem that now appears not to be that there was too much noise on the network, but too little signal from the 2413u. I also suspect that it's possible that the wireless signal from the 2413 may been extremely weak or absent, as deploying a bunch of dual band devices never really fixed the problem. Live and learn.
I also just found out that slow or unsuccessful restart problems on my Mac Mini were not OS problems or even hardware problems, per se, but were a result of some USB device (hub or endpoint) that cratered the Power On Self Test so that it almost never executed successfully. Again, it's a USB issue. Attempting to work around USB problems, I now have a really poorly structured USB hub topology that I will be straightening out. I may have made a separate post about the USB hub problems, so if this is redundant, my apologies.
