Upgrade to Windows 11 using Rufus.

[king1]

converting mbr to gpt can be done using some partition manager programs
eg. the paid version of https://www.partitionwizard.com/
Free version works on data disks, need to pay if you want to use on a system disk.

or via MS disk manager or disk part
https://learn.microsoft.com/en-us/window...a-gpt-disk

But I don't know how successful the PW paid version is, haven't tried it. The MS version suggests all data will be lost.

I ended up backing up the data, converting to GPT then reinstalling windows..

Pretty sure the windows installer won't do this for you ...

As with everything in this area, full system backup before doing anything, just to be safe. Macrium reflect or similar...