After a week of testing I can confirm that the RPI4 LE13 image containing the patch posted by chewitt works flawlessly for me.
I tested after many reboots, shutdowns, even works after ungraceful power-cuts.
I use the same device and the same router as stated before in the GH issue.
So..Can we get an updated patched version for the RPI4?
Or what is the next step?