How does you phone perform when connected to another source of Wi-Fi such as a coffee shop or other person's home broadband router @Sengoku ?
Some troubleshooting tips are > You could try forgetting the network in your phone and set it back up and then see what happens.
And if your router allows it split the frequencies in the router to 2.4GHz and 5GHz and then again firget the network in your phone and then connect to one frequency and then the other to see if that helps.
Your phone has a diagnostic tool in the Samsung Members App under the GetHelp section which you can use.
If I can be of any further help then please don't hesitate. Take care. 😎
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "