The first step fixed it for me instantly. Hope this helps anyone else stuck in "Connecting..." mode!
Samsung Messages is a popular messaging app used by millions of Android users worldwide. However, some users have reported encountering a frustrating issue where chat registration fails, preventing them from sending or receiving messages. If you're experiencing this problem, don't worry – we've got you covered. In this essay, we'll explore the possible causes of the Samsung Messages chat registration failed issue and provide a step-by-step guide on how to fix it.
Turn on Airplane mode, clear the cache for both Samsung Messages and Carrier Services, restart the phone, then turn off Airplane mode. Samsung Messages Chat registration failed
This is a "nuclear option" that fixes deep-seated connectivity bugs. Go to > General Management . Tap Reset > Reset network settings .