The session timeout is 3 hours. So if a user remains inactive for 3 hours, they will get disconnected. Updating the page though will reset this timer.
It has been brought to our attention though, that sometimes the Edge browser might time out sooner, even while navigating in courses. This is not related to TalentLMS, but the specific browser. In this case, we recommend clearing cookies and cache, and if it persists - perhaps using a different browser.