Ubuntu – HDMI to VGA converter connection errors


I'm getting a weird error when connecting my VGA monitor via an Aukey HDMI to VGA adapter to my laptop's HDMI port:

Whether a connection can be established or not (i.e. on startup, when opening system settings or when running xrandr --query) is apparently determined by pure chance; when running xrandr --query multiple times consecutively, it sometimes prints HDMI-1 disconnected and sometimes HDMI-1 connected. But only when it's connected, the monitor is actually working and extends my desktop (this is the expected behavior).

My laptop (later named "Laptop A") is an Acer Aspire VN7-571G-52EP. A Dell XPS 15 ("Laptop B") always connected without problems (running xrandr was not needed to make the monitor work).

I tried different combinations:

Computer | OS                      | Connection  | Monitor          | Result
Laptop A | Ubuntu 17.10            | Converter A | Monitor A (VGA)  | not working
Laptop A | Ubuntu 17.10            | Converter A | Monitor B (VGA)  | not working
Laptop A | Ubuntu 17.10            | HDMI cable  | Monitor C (HDMI) | working
Laptop A | Ubuntu 17.10            | Converter B | Monitor A (VGA)  | not working
Laptop A | Windows 10              | Converter A | Monitor A (VGA)  | working
Laptop A | KDE Neon (Xenial)       | Converter A | Monitor A (VGA)  | not working
         | Live image 20180113     |             |                  | 
Laptop B | KDE Neon (Xenial)       | Converter A | Monitor A (VGA)  | working
         | Up-to-date installation |             |                  | 

Some notes:

  • "not working" means that weird random connection error, "working" means that there were no connection errors (plug and play)
  • Converters A/B are different devices of the same model

These combinations prove that it must be a software problem.

Both laptops have both an intel and an Nvidia graphics card with up-to-date proprietary Nvidia drivers installed (no bumblebee and never tried to enable Nvidia Optimus). Laptop B uses the intel GPU (controllable via nvidia-settings). For Laptop A, the problem couldn't be resolved by using either the intel or Nvidia GPU (using Ubuntu 17.10).

I also tried using Wayland instead of X.Org (on Laptop A), but it never connected to my monitor. Running xrandr didn't help then.

Does anybody have an idea what causes this strange behavior and how to fix it?

Attached logs:

Best Answer

Yup, I've had this before as well and it sometimes happens on cheap low-end laptops with cheap non-powered adapters.

I've never had this happen with externally powered ones so it's a hardware problem on the Acer that was probably solved in the Windows driver (more power output to the port) that hasn't found its way into the Linux driver yet.

Your solutions are:

  • file a bug with both Intel and nVidia
  • buy an externally powered HDMI to VGA adapter for the Acer.
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