No longer able to use cellular data with XR

XR will no longer use cellular data. This problem started Feb 17. Unless connected to WiFi, the phone will not search in safari, will not load map images in apple or Google, will not send or receive images or videos via text, will not send or receive emails, etc. I am using iOS 15.3.1. AT&T carrier is 49.0.2. I’ve turned cellular data off and on, I’ve turned low data mode off and on, I’ve restarted iPhone, I’ve turned cellular data roaming off and on, I’ve ensured cell data is on for maps/messaging/safari/etc. Please advise how to resolve. This is a challenging problem when not on WiFi which happens often during day to day travel. Thanks.