@Debinter if works ok in Safe Mode a third party app/theme may be causing a conflict. An idea also to turn flight Mode on and off before Rebooting.
some other ideas here if not resolved (in case you have not tried some of them)
Go to Settings- Connections - Wi-Fi - Tap the cog symbol to the right of your router - Forget . This is the bottom right on the list. Toggle your Wi-Fi off and on again - Select your router from the list of available connections, and run through all the connection steps.
Thereafter go to Settings - Connections - Wi-Fi - Tap the cog next to your router and view More ,select the MAC Address Type and set this to Phone MAC. If the issue persists, I would suggest pressing the Volume Down and Power buttons together for around 10 seconds until the phone restarts, the reason being that this will refresh the software and address any issues that might be causing problems. An idea also to reboot the router if the issue not solved.
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
