Please be sure to send us error reports using Beta Feedback option in Samsung Members app.
It seems like there are a lot of problems on your device that might be connected to FOTA upgrade.
What you can try is to remove the cache of the device:
1. Backup your data using Smart Switch (it is not necessary to do so, but it always helps to be safe )
2. Turn off your device
3. Press and hold (at the same time) Power button, Volume up button and Bixby button
4. Keep holding them for like 7 seconds (At first you will see the Samsung logo, but do not release your fingers yet. Once the screen changes then you can release it)
5. Use Volume keys to move up and down and Power key to select an option - Select "Wipe cache partition"
6. Confirm it
7. Select "Reboot system now"
If that did not help, then it might be necessary to factory reset the device (Remember to backup first!).
I hope that this will help you out!