WiFi connected but no internet

Hi,
I recently bought a Tab S6 for my partner but am having a problem with the WiFi.
It will be connected fine then randomly out of the blue the internet will stop working and the WiFi symbol will have an exclamation mark next to it.
The only way to fix it is to disconnect and reconnect WiFi - untill it happens again.
All my other devices connect to the same WiFi network fine without any problems.
Any help please?

Thanks