I've installed Buster on a Dell Inspiron 1501 laptop. I have it connected to
an external monitor, keyboard, and mouse via a KVM switch.
I thouight all was well, but now, a day later (with the KVM switched to other
computers), switching the KVM back to the laptop, the external monitor,
keyboard, and mouse are no longer enabled. (They still work fine for any of
the other computers.)
I used to use those a *lot*! I guess that the beginning of the end, was when *they* decided to Deprecate the PS2 Connections.
I generally "reserved" one Port for "transient" (i.e. Laptop) computers. I occasionally encountered your issue, when the Laptop went to sleep. My workaround (when rebooting was not practical) was to bring Video back first, using the Video Settings screen and bringing back the Second Screen. I typically didn't go past that, as I was usually able to function, using the Laptop Keyboard and (most commonly) Trackpad.
I suspect that if I reboot the laptop, or maybe even if I logout of the
current user and back in, I might get the external monitor, keyboard, and
mouse re-enabled, but I don't really want to do either -- as is often the
case, I have various files and such open and to an appropriate place that I
don't want to lose (nor have to re-establish).
Rebooting always worked for me.
So, that leads to two questions:
1. Is there a way to re-enable the external monitor, keyboard, and mouse
without doing something like rebooting?
See above for Video. I'll leave Keyboard and Mouse for others.
2. Is there a way (a setting to change) to keep the problem from recurring in
the future?
Yes: Ensure that the Laptop doesn't go to Sleep.
One more "extra credit" OT question (which I can ask in a future thread if no
one responds here) -- how can I tell whether the Buster installation is using
X or Wayland?
I am also interested in this Answer.
Kenneth Parker