S9 wifi can not share connection via wifi anymore

[Android Central Question]

I used to be able to connect my phone to the local free telstra (australia) hotspot and then turn on hotspot on my phone and share that connection.
But after yesterday, now when i try to turn on mobile hotspot, it says "to enable mobile hotspot, wifi needs to be turned off" and it turns off wifi which of course turns off my telstra connection.
This seems strange because it worked just fine for the last six months.
Does anyone know what's happened?

 

[Rukbat]

The WiFi went from duplex to simplex. There are tethering apps in Play that can do it the old way. (The new way is to share mobile data via WiFi.)