The setup is as follows (iivs can correct me if i'm wrong):
Server is running on one computer while posgresql database is running on the other computer. The computer with database is put to sleep and when it is awaken server might exit (it has happened at least twice).

Not much in the logs - a lot of reconnection attempts and then finally:

22633:20200123:101341.859 query [txnlev:0] [select oid from pg_type where typname='bytea']
 22633:20200123:101341.859 [Z3005] query failed: [0] result is NULL [select oid from pg_type where typname='bytea']
 22633:20200123:101341.859 [Z3005] query failed: [0] PGRES_FATAL_ERROR [select oid from pg_type where typname='bytea']
 22633:20200123:101341.859 Cannot connect to the database. Exiting...

It would seem that during system wakeup posgresql responded with error that was deemed not recoverable and server exited.