Hey @goldwrt thanks for responding! I will need to check if your suggestion works during this week, I remember noticing that there was very little space left after installing OpenWrt so maybe I installed it on the wrong partition.
I do notice that my boot menu has more entries so it must be a different uboot version as well. I have implemented the ESP hack at the moment and now am learning my ways with OpenWrt, I realized that a nice thing about this hack is that I can make that ESP into a remote serial interface for my router btw 
so no need to ever tether to the router again.
I’m wondering if all 3 radios on this router should be useable to set up APs on them, or if one of the radios (presumably the 6Ghz one) isn’t supported yet, as I couldn’t get it to work.