How to boot from Win11 DVD£

Dear Shk,
Before installing Windows 11, you must enable the built in Platform trust module, and set CSM to disabled.
This will install Windows in UEFI (GPT) mode.
However it depends on, if your graphics card supports GOP, if not you cannot disable CSM, built in graphics, does support Graphics output protocol.
You can use the following trick to get aoround the boot problem
1. you can press F11 to get into the bootmenu, and select the UEFI DVD drive, this will then install Windows in GPT mode
2. format a USB stick of 8GB or above under NTFS, google for emdia creation tool, and download the latest release of Windows, and let it create an installation media on USB, again reboor, press F11, and select the USB device.
Depending on the Windows version, home, or Pro, you need to use a Microsoft account (like hotmail.com or so) to be able to install Windows 11, this is only needed when you have Windows 11 home.
With Windows 11 pro this is not a problem.
When your system had an actiavted Windows 10, you can also upgrade, but the system MUST be installed in GPT mode.
you can use a microsft tool like mbr2gpt. to convert it.
Or you can do a clean installation of Windows 11 in GPT mode, once the system is conencted to internet, it will use the Windows 10 activation stored in the Microsoft cloud, to activate.