it depends from your settings, i was poking at this topic:
https://bitcointalk.org/index.php?action=profile;u=1141938;sa=showPostsAnd when i done every step, there was some checkbox, that shown something along this line "Shutdown at 90C"... So you can see your settings and edit them. What are your current temperatures? Can you post screenshot of your UI with temps?
Yes , check your temps, I had a S9 recently set to shut off at 70c from the manufacture, it would run for 10 min then stop....
Also please post your Kernel log it will tell you why the miner shut off or lost connection