I have installed PostgreSQL on two different Windows 10 systems and am having the same problem.  The server work great when I first connect to it but if I disconnect client and come back a few hours or a day later I am unable to connect to the service with a timeout error.   I have used both pgAdmin and DBeaver as clients.

If I do a restart on the window service everything works fine again until I disconnect the client for a extended period.  Can't find anywhere else this issue is discussed.   

Have used both the latest 11.2 release and an older 10.x release and both operate the same.  Is this a known issue?  Is there a solution?

Have you checked logs (Event viewer or the folder /data/pg_log)?

Cheers

Moreno.-