Since the September update my Note 9 many times a day says no internet connection. I didn't have an issue before my phone updated on September 14th. I could be on wifi and still get the pop up! The only way to fix is to restart my phone.
Have you tried any of the standard fixes? You didn't mention anything that you've attempted so far. Are you just getting the pop up or are you actually loosing network connection??
Try to clear the Cache Partition.
You can try to reset all network connections.
This will reset all your network connections. Wifi, bluetooth, everything. You will have to re-pair all your connections when you are done.