I have never had this many problems with a phone in my life! I bought the Note 20 Ultra 5G 512G and spent $500 dollars with $900 remaining on this phone. All my problems started when I downloaded the UI 3.0 Android 11, my phone started glitching when I would toggle between different apps while having those said apps open at the same time. I'm having WIFI connection issues which Samsung blames T-mobile. I've troubleshooted everything with T-mobile to no avail. My phone logged me out of all my important apps.
For network reset: From settings > General management > Reset > Reset Network Settings
(BEAWARE THIS WILL UN INSTALL YOUR WIFI AND BLUETOOTH DEVICES AND AFTERWARDS YOU WILL NEED TO RE INSTALL YOUR WIFI AND BLUETOOTH DEVICES)
I also had a problem with my network/phone. I did this reset my modem, and I was all good