I have an Acer Aspire E5-521 for a while now. It is working great. I've been using it for work, along with an external monitor connected to the VGA port on the left-hand side of the laptop. Windows 10 is set to extend the desktop to this second monitor. This way, I have half of the desktop displaying on the native screen and the second half on the external monitor. Everything works great this way. Now I want to have a second external screen connected to the HDMI port of the laptop so my desktop would span on three screens (1/3 of the desktop on the native screen, 1/3 of the desktop on monitor 1 (VGA port) and 1/3 of the desktop on monitor 2 (HDMI port)). However it doesn't work. As soon as I connect the HDMI cable to the laptop, the screen connected to the VGA port turn black and only the HDMI port's screen display half of the desktop. If I disconnect the HDMI cable, the VGA's screen wakes up and display half of the desktop. I tried swapping both monitor (because both monitor are the exact same HP model with both VGA and HDMI input port) and the problem is still. I looked in Windows settings and find all 3 screens connected, when looking in "display settings" but there's always one screen disabled and I can't enable it or change the settings. It's greyed. AMD Control Center is no help either as it only let me change setting for the two monitors enabled. Seems like Windows is hiding the third "disabled" monitor to the graphics card driver. Looks like the laptop can't handle two external screen at the same time. Or at least, can't handle output from HDMI and VGA at the same time. Looking to the BIOS is no help either.
After a bit of Googling, it looks like I am not the only one having such problem but can't find any solution. I'm wondering if one of you already manage to have 2 external monitor displaying at the same time on a similar laptop.