I have a note 20 ultra and I have mobile network connection problems very slow to connect. I have all the bars and the 5G connection and can have a 70 to 80 dBm signal strength but still takes a very long time to connect and start loading data. I have had the phone since December and only about 3 times have I had speeds about 200 to 400. I live in Houston TX on T-Mobile. I bought my phone from Samsung unlocked. I sent it to Samsung under the warranty and this is their report.
"Thank you for giving us the opportunity to ensure you have the best experience with your Samsung product. A Samsung Certified Pro has performed a thorough examination of your device and after our analysis no defect was found. In order to validate this finding your device has passed the full array of functional tests, is confirmed to have the latest applicable software version and has passed all quality control functions successfully.