The next time I come in on my laptop, I have to sign in again.

Running that will clear the browser cache and/or cookies? That will also clear saved passwords and could be your culprit.

On Edit: There's an option on DU login page to Stay Logged in on this Device. Have you seen that and checked the box?

or have some extension or app that's clearing your browser cookies. That is a good idea but if so, one should make an exception for DU.

Ad blockers and tracker blockers don't seem to affect DU logins.

Private mode is real easy to punch on an iPhone by accident.

I have an app on my desktop that clears all browser(s) history, cookies and data.

But I am pretty careful and rarely lose the DU login cookie.

🍀🍀🍀🍀🍀 Good luck. 🍀🍀🍀🍀🍀

...I myself frequently overlook the obvious.

Are you ticking the "Stay logged in on this device" box on the sign-in page?

If not something may be eating your cookies. Is your browser set to clear cookies on exit?

Is something in your privacy settings or apps doing that?

Are you logged into the browser as a guest or incognito?

Good Luck!