I have a Galaxy s6 that often doesn't receive every text message being sent to me. Nor does the receipiant always receive my response. I have tried switching between stock messages, message+, and Google Messages. Nothing seems to be fixing the issue. I know this phone is extremely outdated, and that the apps may not perform as they would with newer models.
On other days I will recieve or send duplicate messages. I often restart the phone hoping to fix the issue but it doesn't seem to help.