Some messages can be received, others can't. Mobile 4G card, what's going on? Does anyone know?

Because of the delay of CSFB, SMS seems to be CSFB's, just like calling with 4G is sometimes delayed. When talking and texting, you have to switch from 4G to 3G or 2G network. When the signal is bad, the delay is a bit long. If the 4G is turned off directly, the time for him to stay connected to the 3 or 2G network will be quite short. There is no solution at present, depending on how your local mobile optimization is progressing.