iphone 15 pro wifi keeps disconnecting

Since I got the iphone 15 pro I am having problems with my wifi. The WiFi keeps disconnecting from time to time (sometimes once or twice a day and sometimes five times in one hour).

when I turn off the WiFi and on again it is connecting fine.

setup:

TP link deco with 4 accespoints in house, one on each floor. Sending 2.4GHz and 5GHz. Why 4 accespoints? I live in a house full of thick concrete walls and 3 floors with large backyard (total house is 330 square meters)

funny thing:

• Samsung galaxy S23 no problems
• iPad air no problems
• iPad Pro no problems
• iphone SE no problems
• other devices like HP pro books no problems
• iphone 12 Pro Max no problems (the iPhone I had before the 15 pro)

already tried with apple support:

• resetting network settings
• resetting whole
• factory reset iPhone 15 pro with restore from iCloud
• factory reset iPhone and clean install with itunes
• turn off WiFi assistance from 5G network when WiFi signal is weak

already tried on the network settings:

• set the internet tot 2.4GHz only
• turn off seamless switching between accespoints (because it seems like this only happens when the phone switches from AP al lot)
• fixate the phone to one accespoint (worked but it has no connection on the second floor)

I am starting to think the iPhone 15 pro does not like accespoints in a house.

I am really out of ideas…