Thank you very much for the help, Sk8. I'm pretty much in the same boat as you, I work for a healthcare agency with 200+ field staff that use iPhones to provide hotspots for their Windows 7 laptops. For us, this issue has been awful. Windows 10 doesn't seem to be affected by this, so upgrading from 7 to 10 would be a permanent fix, but again the nature of my job prohibits a quick rollout of this to 200+ people. At any rate, creating a batch file to run the ipconfig /release /renew was excellent advice! It lasts for a day or two until the IP reservation ends and needs to be ran again, but it's much better than nothing. I called Apple Support a week ago regarding this, and he completely dismissed the idea it was caused by iOS 13.1.. even though everything was completely fine before that and there's plenty of postings on forum boards about it. He went on to suggest it was something on our end with our loadout, which is obviously complete BS. I gave him all of the information from my findings and testing, but he was resigned to the idea that it was on our end. I've lost a ton of respect for Apple.
For anyone else reading this, I just wanted to point out that nothing else worked for me besides the command prompt. Resetting network settings, renaming the hotspot SSID, changing hotspot password, deleting the stored network creds from laptop, hard rebooting the iPhone, etc etc etc.
I certainly hope Apple realizes this is THEIR fault and have their engineers fix this mess.