Personal Hotspot not available

I no longer have the option to activate personal hotspot on iPhone 11 running ios14.  There is no activation option in settings. It does appear in the Control Center drop down menu, but the button is greyed out and won't turn on.

    The problem was evident on my iphone 11 even on ios13.  It became an issue last week when I was on a departing plane at the airport and wanted to connect my PC to a personal hotspot. Much more of an issue last night when there was a widespread Xfinity outage for several hours which affected home broadband.  Mobile broadband still worked and it would have been a usable lifeline if I could have tethered my PC to my working iPhone.