On the Samsung device, the mobile WLAN hotspot is automatically switched off after 20 minutes of inactivity (no connected devices), and if this is not desired, the time car can be shortened, extended or even completely deactivated.

Android 10 (One UI 2.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Connections
Step 3:  Tap on  Mobile Hotspot and Tethering
Step 4:  Tap on  Mobile Hotspot
Step 5:  Open the  menu
Step 6:  Tap on  Timeout settings
Step 7:  Choose  Timeout  you want
  1. Open the Settings
  2. Tap on Connections
  3. Tap on Mobile Hotspot and Tethering
  4. Tap on Mobile Hotspot
  5. Open the menu
  6. Tap on Timeout settings
  7. Choose Timeout you want

Samsung Instructions