MacBook not recognising USB devices

This is the second time my (2015) Macbook has failed to recognise devices attached to an Apple USB/HDMI adapter. The fix is an SMC reset ( https://support.apple.com/en-au/HT201295 ) but I hope it does not indicate a failing motherboard or similar!

Symptoms are failure to mount an external hard disk and failure to connect to an external display via HDMI. It may be worth connecting them from time to time to check the Macbook.

I have tried other adapters and they also don’t work until the SMC reset.

I will try to keep my backup SSD disk up-to-date while travelling - just in case!

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Port failure used to be a more common problem—for which an SMC reset was the solution. That it still happens is regrettable, but not surprising. I doubt it’s a problem with your motherboard. It is a power issue; the Mac sometimes looses track of the power requirements of various IO devices. An SMC reset usually straightens things out.

I am still having no luck connecting my Retina Macbook to a display via HDMI. I have tried SMC and NVRAM resets. I just tried a direct USB-C to (male) HMDI cable - it worked with my iMac but not the Macbook.
The only way I can currently use an external monitor with the Macbook is via the Apple VGA adapter, after an SMC reset. VGA resolution is useless, of course, but at least I know the Macbook can output graphics.
Searching the web I found numerous reports of people having problems after installing High Sierra (HDMI worked fine when I first purchased the Macbook in 2015). It seems that Mojave inherited the same “bug” and that Apple does not recognise it as something worth fixing.
BTW I am not installing Catalina but would like to hear from anyone who has installed it and has HDMI working reliably with their Macbook.

I have no help to offer, but my MacBook (Retina, 12-inch, Early 2015) with 10.14.6 Mojave has connected to an Acer display using a USB-C hub and an HDMI cable. Very infrequently, I have had anomalous video that I fixed by unplugging and replugging the USB-C cable, but I don’t recall if that was with the USB-C hub or not. For what it’s worth, I went from El Capitan to Mojave in one jump (and have regretted it ever since, but that’s a different story) and thus skipped High Sierra.