Anyone ever have an issue with Wifi where it keeps disconnecting even though your other devices connect just fine? It just keeps turning off and saying "Connected without Internet".
This was a known issue. Updates should fixed the problem but sometimes an update doesn't completely work.
I would reset the phone if the issue persists.
Unfortunately with Samsung devices you can't completely wipe the device and flash the firmware and start over with the latest update. I have complained to Samsung about this. You used to be able to do it with a program like Smart Switch.
Pixel and iPhone you can do this and it can be really helpful for persistent or intermittent issues.
The other thing you can try instead of a complete reset is to just reset the wifi and cellular. You will have to enter your wifi password again but this alone might solve the situation. Can't hurt to try first.