Hello,
I resolved the issue! With catlog installed, I had proper error messages to search for. The solution is in this thread post 15 from tobika. Somehow FDroid has a bug inserting wrong data those two files
/data/misc/wifi/wpa_supplicant.conf
/data/misc/wifi/p2p_supplicant.conf
I removed those files using the root explorer amaze. After a reebot, everything works fine again.
Many Thanks for helping!!