I have an S9+ and I updated the other night to Android 10. Since the update I can no longer stream over my data plan. Sprint has done all sorts of reboots and resets to my phone and the only thing they can say is that it's an issue on the Samsung side.
So how do I fix it? I am all sorts of angry about this.
The best way I've found to see if the issue is network , sim card or phone related is to as a process of elimination try your sim card in another phone and then another sim card in your phone.
I've updated my Note 10+ 5G to Android 10 a few weeks ago and have experienced no issues in regards to what you are experiencing @TMccall
A Samsung Experience Store or Samsung Service Centre can run a diagnostic on the phone.
I wish you all the best with this situation.
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.