External monitor stuck at lower resolution; changes end up crashing hyprland

[Michota]

External Ultrawide Monitor (Dell U3415W) Stuck at Lower Resolution, Fails to Apply Correct Mode

TL;DR:

External monitor Dell U3415W connected via HDMI-A-2 or DP-3 on Hyprland only runs at lower resolution than native 3440x1440. Attempts to set native resolution cause screen freeze and unusable display state. Disabling laptop internal screen temporarily fixes resolution but does not persist after reboot. This problem does not occur in Windows with the same hardware and cable.

Issue Description:

HDMI-A-2 always works on Hyprland, but only at a lower resolution than highest possible. Setting 3440x1440@49.99Hz in config causes the monitor to momentarily turn black, then display comes back but freezed and with same old resolution, the monitor’s image (not the OS). The extra screen space is unused and the content is shifted to the left. Disabling the laptop’s internal screen (eDP-1) and reloading config lets the external monitor work at full resolution, but this doesn’t persist after reboot or re-saving the config (when i restart the laptop, the main monitor is still disabled, but HDMI-A-2 is back to lower resolution). tofi (the app runner) sometimes crashes after these events. The monitor works perfectly at full res under Windows 11 with the same laptop & cable. Disabling eDP-1 in Hyprland only disables the display in software—the hardware backlight and controls are still active.

Additionally, I have tested with DP-3 as well, which in hyprctl monitors even shows support for up to 3440x1440@59.97Hz, but it exhibits exactly the same issue as HDMI-2 described above—failing to apply proper resolution, screen freezing, and unusable extra screen space. So the problem is not HDMI-specific.

Description

System:

• Laptop: Thinkpad P52s
• External monitor: Dell U3415W (HDMI-A-2; native [3440x1440@49.99Hz with HDMI, 3440x1440@59.99Hz with DisplayPort)
• Hyprland (newest, 0.50.1)
• HDMI 1.4 Cable
• DisplayPort Cable
• Same setup/cables works flawlessly in Windows 11

Observed behaviour:

• HDMI-A-2 is always connected and detected, but only runs at a lower resolution (2560x1440).
• Attempting to set 3440x1440@49.99Hz via Hyprland config causes:
  • Monitor screen blacks out momentarily.
  • When it comes back, the higher resolution is not applied. The screen content is shifted to the left, the extra space unused, and the monitor image is frozen (OS still works, but the visible image does not update).
• The very same issue occurs on DP-3, even though hyprctl monitors shows it supports up to 3440x1440@59.97Hz.
• gtf/modeline tweaks do not fix the issue.
• Disabling or enabling eDP-1 (laptop display) has no impact on HDMI-A-2’s behaviour; HDMI-A-2 always shows something, just not at the requested resolution.
• If I:
  1. Start PC
  2. Set/configure high resolution in Hyprland (monitor then freezes)
  3. Disable laptop screen in config and reload (actions taken on laptop display)
  4. Now HDMI-A-2 appears at correct resolution …but this does not persist after reboot or any Hyprland config reload.
• tofi launcher crashes after these monitor config events (may be related to how surfaces are handled on monitor events).

Other notes:

• Disabling eDP-1 in Hyprland disables it only in software (screen remains illuminated, brightness can be changed).
• The problem does not occur in Windows with identical setup.
• No way to make high-res output “stick” on Hyprland after reboot or config save.
• When the screen is freezed, moving the cursor won't move it, but IT WILL CHANGE IT'S ICON (e.g. when it will hover a text, it changes to this roman-one [I], when its on something pressable, it will change to the finger-pointing state), so it seems like the content is freezed, but not whole monitor!

Please, help!

[Michota]

New discovery:
Using following fixes most of issues, and the resoltuion is as intended, but it takes additional 2 seconds to see something, which looks like longer hyprland boot-up, but in fact its the monitor taking a while to load higher res.
So it fixes most bugs, but seems to be rather a patch than an actual solution

This disables the built-in monitor, causing hyprctl to re-load, and use the DP-3 monitor with best settings possible.

// hyprland.conf
exec-once = hyprctl keyword monitor "eDP-1, disable"

Downsides:

• The default workspace for external monitor (DP-3) is the second workspace (2)

[VeryFunnyMonkey]

Hey, can confirm im also getting the exact same issue.

The exec-once workaround also works for me.

Did you have any further updates? I will play around with it and see what else I can find

[Michota]

Did you have any further updates?

sadly, nope.