Messages to Android won't send

I've had my iPhone XR for a few months, but recently I've had trouble sending SMS and MMS to androids. My friends send me pics and I never get them, or get them in about 15 hrs.

Worked great until just a few days ago. Sometimes the SMS messages don't send at all unless I turn on airplane mode and then leave the data on without wifi.

Any ideas what's wrong? I already tried restarting my phone, but no dice as far as I've noticed.