My (non-tech savvy) friend and I have been having a weird issue where random texts show up like 2 days later. My phone is up-to-date and new and his might never have installed a system update for all I know. (I don’t let him connect to my main WiFi network for a reason.)

I don’t seem to be having this issue with anyone else. I’m on iOS and he’s on Android but a relatively modern Samsung phone. Should I sit him down and update his phone or something or is this a known issue?