I own a Samsung Galaxy s9 and currently my mobile hotspot isn't working correctly. It promts connected devices to "sign in to network." Previously this wasn't a problem.
I've checked my data usage for Hotspot and I've used 1/3rd of the data. So I know I haven't run out.
I've tried resetting my phone and connected devices. I've tried changing the Hotspot name as well as password. I've tried forgetting the Wifi name on my connected devices. I've also tried the "Add device" and only allow selected devices.