Try refreshing your server search more often. Or log back into your Steam profile. This happens to me too.

It's better to click on the star and add servers to your favorites, it will be easier to find.

Hello.
Was this an issue previously or did this just started to occur recently? This also might be difficult to debug as the issue might lie on the network of the machine that runs the DayZ which is not your computer since you are using GeForce now.

This problem never happened before (I've been playing for about a month). It suddenly appeared from one day to the next. I didn't change any settings.

I will check the situation again today and let you know if the problem still occurs.

Everything's working fine now (even though I haven't changed anything in the settings). Is it possible this is a common problem with the official launcher, which can come and go on its own?

Hard to tell as we had no experienced this problem nor we can reproduce it. It could also be something with the machine and its network that is hosting the game for you