MatteoDXB.
As stated on: https://openwrt.org/toh/d-link/dir-2640_a1
At the bottom is written: MT7615N 5 GHz Problems - see [Solved] OpenWrt on MT7621/MT7615N devices with 5GHz problems
So better read this 1st and see: The 22.03.3 Stable release appears to have least amount of problems as of January 2023. But, expect a loss in routing performance since it does not include arinc9's patches.
Conclusion: There are some issues regarding 5GHz Wifi, so better stay on 22.03.3
DG.