Open Settings
Go to System
Select Power & sleep or Power & battery
Set Sleep to Never
Set Screen timeout to Never or a longer time
Check Advanced power settings
Set Sleep after to Never
Disable Hibernate if needed
Keep the computer plugged in if required
Use a power plan that prevents sleep
On Mac, open System Settings
Go to Lock Screen or Battery
Set Turn display off on battery and on power to Never or a longer time
Enable Prevent automatic sleeping when the display is off if available
Use Terminal command caffeinate on Mac if needed
Keep an app or presentation mode active if allowed by your system
Check for company or school policies that may override sleep settings