Linux Dual Monitor Issues (Mirroring / Extend / Not Detected) — Fix

If your second monitor is not detected, keeps reverting to the wrong resolution, flickers, or you can’t switch between Mirror and Extend mode, the cause is usually one of: GPU drivers, cable/port compatibility, refresh-rate mismatch, or display server quirks (Wayland vs Xorg).

Step 1: Quick Hardware Checks (Very Common Fix)

• Power-cycle the monitor (turn off, unplug 10 seconds, plug back in).
• Try a different cable (cheap HDMI cables cause real problems at 4K / high refresh).
• Try a different port on the PC (HDMI vs DisplayPort).
• Avoid docking stations / USB display adapters during troubleshooting.
• If using an adapter (DP→HDMI / USB-C→HDMI), test a different adapter.

Step 2: Install All Updates (Recommended)

Many display bugs are fixed in kernel, Mesa, and driver updates. Install all available updates, then reboot.

sudo apt update
sudo apt upgrade -y
sudo reboot

Step 3: Check Driver Manager (GPU Drivers)

On Linux Mint / Ubuntu-based systems, open Driver Manager (or “Additional Drivers”) and confirm the correct graphics driver is selected. Apply changes and reboot.

Step 4: Set Mirror / Extend Correctly

Open Settings → Display and choose the mode:

• Extend: two screens act as one large desktop (most common)
• Mirror: both screens show the same image
• Confirm the correct primary display is selected
• Match a stable refresh rate (try 60Hz if you have flicker or blackouts)

Step 5: Try Switching Wayland / Xorg (Ubuntu GNOME)

Some multi-monitor + GPU combinations behave better on one display server than the other.

• Log out
• On the login screen, click the gear icon
• Try “Ubuntu” (Wayland) vs “Ubuntu on Xorg”
• Log in and test displays again

Need Help?

Send us your Linux distro version, GPU type (NVIDIA/AMD/Intel), and monitor connection type (HDMI/DP/USB-C), plus a photo of your Display Settings screen — we’ll guide you.

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