Is it a mobile phone problem or a network problem that the text message sent on the first day is received on the third day?

Whether the text message sent on the first day is received on the third day is a mobile phone problem or a network problem depends:

If the receiver's mobile phone is turned on normally, but the network is not good, it is the receiver's network problem;

If the receiver's mobile phone has a problem or is turned off, it is not a network problem until it is restored;

If the sender's network is not good, which leads to the failure of the short message, it is still successful after many attempts. This is the sender's network problem.