Logic Masters Deutschland e.V.

This puzzle has been my ninth feature on Cracking the Cryptic (click here to see Mark solving it) and it is a puzzle with an empty grid, which feels always special for me. I hope that you enjoy the puzzle. Constructive feedback is always appreciated! The rules are as follows:
Normal Sudoku rules apply. Cells that are a king's move apart are not allowed to contain identical digit. The digit in the central cell of each box has to be less or equal than the box number. Boxes are numbered in normal reading order. Each horizontal 3x1 region that is completely contained in a single box has to sum to the same value. Each vertical 1x3 region that is completely contained in a single box has to sum to the same value. The digit in the top-left cell and the digit in the bottom-right cell of the grid must sum to 3.
You can play this puzzle via the following link: https://sudokupad.app/jf0yny3xul