The fix is very simple, but not for most end users unfortunately. The problem is the iOS 13.1 and newer HotSpot DHCP server is not working correctly, it is handing out bogus IP address info on initial connection. To fix this quickly, connect to the HotSpot, get a non functional IP address, remain connected to the HotSpot, open a command prompt on Windows, then run two commands: ipconfig /release and then ipconfig /renew
You will now obtain a new and valid IP address from the HotSpot DHCP server and your connection will work again properly.
The issue seems to return after some amount of time or combination of events; so do the same procedure again when and/or if the issue returns.
You can make a simple batch file and save it to your desktop to quickly double click and perform the IP address refresh to fix it again.
Apple, you really need to acknowledge this problem in iOS 13.1 and newer, and then fix the problem please, it is wreaking havoc in our small enterprise with 600 plus iPhones deployed here to my end users! Please fix ASAP!
PS: You can use the same steps on a macOS or iOS device to refresh a client IP address, though the procedure is a little different on each.