As per your query, kindly perform the following steps to resolve your issue.
Forget the Network: Settings > Connections > Wi-Fi > Wi-Fi network > Tap and hold the Wi-Fi network that you're having trouble with until the menu allows you to select Forget Network.
Restart the Router and Mobile Device.
Reset settings: Settings > General Management > Reset. Reset network settings: Reset Wi-Fi, Bluetooth, and other network settings to their default.
If the issue persists kindly report the problems with a log file. To share a log file, click on the Samsung Members Application (Open Samsung Members Application > Support> Tap on error report > Type your query > Send).
