How to change resolution of xcp-ng/XenServer VM (windows)?

Follow the following steps

Start in Recovery Mode

Windows 10

1. Open the Windows Settings
2. Click the Update & Security button
3. Under the recovery tab, press the Restart now button.

Windows 11

1. Press the Windows key to bring up the Start menu.
2. Next, press and hold the Shift key and click on the power icon from the Start icon.
3. Click on Restart once again at the confirmation prompt and wait until your PC boots directly into the recovery menu.

Set Resolution

1. Navigate to Troubleshoot > Advanced Options > UEFI firmware settings.
2. Press Restart. During restart, the UEFI settings menu loads.
3. Navigate to Device Manager > OVMF Platform Configuration. This displays the current screen resolution.
4. Press Enter to see the screen resolution options.
5. Use the arrow keys to select the desired screen resolution and press Enter.
6. Press F10 to save the changes and confirm your choice.
7. Reboot the VM to see the XenCenter console in an updated screen resolution.