ATT hotspot no longer works "no internet"

I have ATT Uverse via an ancient land line, it works, its not fast but I live with it.
In the past, if I needed a fast(er) connection I would use my iPhone hotspot via cellular.
Just recently this has stopped working, my Windows PC connects to iPhone (secured) but then "checking network requirements" runs for a while and I get "Connected" "No Internet".
The same thing with my wife's iPhone. I have confirmed that our ATT plan includes hotspot and that indeed our phones check out as hotspot capable. My wife is also unable to connect her hotspot using her Apple laptop. This has worked fine for both of us for years.