Diagnosis
The Nintendo Switch outputs a maximum of 1080p in docked mode unless the game and system settings specifically support 4K. The monitor is just displaying the signal it receives.
How to Fix It
The Switch itself cannot output a native 4K signal for games. The monitor's 4K upscaling is what you need to engage.
- Ensure your Switch is in the dock and the dock is connected to the monitor via a High-Speed HDMI cable (use the one that came with the monitor or a certified one) to the monitor's HDMI 2 or HDMI 1 port.
- On the monitor, press the joystick. Go to Picture > Display Mode. Select Display. This enables the monitor's internal scaler to upscale the 1080p signal from the Switch to fit the 4K panel.
- On the Switch, go to System Settings > TV Settings > TV Resolution and set it to Automatic or 1080p.
If That Didn't Work
Try a different HDMI cable. A poor-quality cable may not handshake properly, forcing the Switch to a lower resolution like 720p.
Heads Up
This is upscaled 4K, not native. It will look sharper than a 1080p monitor but not as detailed as a native 4K source like a PS5 or PC. For the best motion clarity with the Switch, also go to the OSD under Picture > AMA and set it to Premium.