Question Dual monitor, issues when changing input on one monitor - monitor still "detected" despite no longer input

Oct 26, 2021
I wonder if anyone's ever had this issue, my google-fu pointed me to all sorts of completely different issues that had nothing to do with mine - mostly pages and pages of "can 't dual monitor", whereas I have somewhat of the opposite.

I run under a dual machine, dual display setup, where two machines share one display under an HDMI switch, and a secondary display is always on the desktop. I just changed my display setup a bit, and I've been running into a new issue.

My old setup: Desktop PC had one DP to HDMI cable going to a HDMI switch, and one HDMI going to the secondary display (my graphics card on my PC only has one HDMI, and three DP ports, none of my old monitors had DP, hence the DP to HDMI cable). Laptop had one HDMI going to the HDMI switch (and obviously its own screen, when lid open). The HDMI switch was going to the main display. Both ASUS displays, 24inch, 1080p. Switch also handled USB switching between machines, for KB+M sharing.

Normally, the desktop would have full control on both displays, but when I needed to use the laptop on the main display, I would press the switch, and my laptop would be on the the main monitor with KB+M going to the laptop as well. Desktop would react by reverting to a "single display" on the secondary monitor (I'd control the mouse cursor, when needed, using a controller with Gopher - it would be really minimal use, but useful). All my Windows desktop would converge to the single, secondary screen. When I'd need to go back to the PC being on the main display + secondary, I would hit the switch, and the desktop would react by resuming the dual display setup. Both Desktop and Laptop were set to 'Extend these displays'. When the switch was pointing to the laptop, the "main" display would effectively no longer be detected by the desktop.

With my new setup, I just purchased a nice new monitor (LG 27GL83A-B). It's the new "main" display. The new monitor comes with multiple inputs (DP, HDMI1 and HDMI2). Desktop is hooked to the new main display via DP, and second display via HDMI. Laptop is hooked to the new main display via one of the HDMI ports. I figured I would only need to switch the input on the monitor, which is easy to achieve with two clicks of a button, to achieve the same results as before (I still use the HDMI switcher solely as a USB input switch at this point for KB+M).

The problem is... When I switch the Main monitor from the DP input to the HDMI to see the laptop on the main monitor, my Windows PC doesn't detect the change in screen setup and still thinks it's connected to the new main display, so it doesn't rearrange the display to the secondary monitor. All my main desktop work, icons, mouse, all stay as if they were on the main display. Same with the laptop if I switch the main monitor back to the DP input, it still thinks it's connected to the main display. I can see that in the Display Settings, both monitors are being detected, nothing changes.

Is this something that's fixable in Windows, or is it an issue at the monitor level where it's not properly communicating to Windows that the display has changed input and is no longer a valid display?

I'm hoping it's something that can be fixed within Windows, I've got the new monitor all nice and setup, it's working great, and would like to keep my old functionality while enjoying the advantages of using DP for my main desktop/monitor connection, without having to goof around in Display Properties every time I switch the input on the new display, or physically unplug the cables... That would just be a major pain...

Any help would be appreciated!