Windows 10: My second monitor is not being detected while it is mirroring my first monitor

My second monitor is not being detected while it is mirroring my first monitor. I have been trying everything to troubleshoot this issue for 2 days now but it has not fixed its self

:)

 

Windows 10 will not detect second monitor and just mirrors the display

Hi

My son has a gaming pc with a new NVidia video card and running Windows 10 I believe and we have just purchased an ultra wide gaming monitor for his birthday.

He wishes to keep his AOC existing monitor and have 2 monitors up and running and to extend the display and not mirror.

We have connected both via HDMI using I think the term is a HDMI splitter purchased from Amazon.

We have updated the Nvidia drivers as suggested and ensured all the cables are connected but when we go to Settings and additional display it does not detect the second monitor and the display is mirrored with no option to extend.

Searched on the web for half a day with no real suggestions. I use 2 monitors at work without issue so cannot explain to him why it will not detect the 2nd display.

Any help would be greatly appreciated. Thanks.

 

2nd Monitor not detected

I have same problem. Last night windows 10 did what was listed as the winter update. Since then my second monitor just mirrors the first monitor. Everything worked until the update. I have tried several things, booting with just the one monitor (ASUS)
and delecting the first (ACER) and then adding both monitors, the control panel just sees the acer monitor. When I ask to detect second monitor it says second monitor not detected. I tried several different resolutions, that didn't help either. The same
screen appears now on both monitors, but control panel senses only the acer monitor.

 

windows 11 cannot detect my second monitor

Windows 11 cannot detect my second monitor. Help. I did all the suggested troubleshooting steps but nothing seems to work.