SOLUTION
The problem is that iOS15 only supports Hotspot wifi connections that have WPA3 encryption.
With the update to iOS15 iPhones/iPads will not allow Hotspot connections to any device that has only WPA2/WPA encryption - which older laptops used.
Solution - buy a Wifi USB adaptor that supports WPA3 and plug it in to one of your USB ports on your laptop. You can find them under $40.
for Surface Pro 3 laptops - the default wifi driver does not allow for WPA3 connection. BUT you can see the fix at the Apple Communities
The driver can be updated by following the suggestion there.
Jack123654
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