How connect to DB PosgreSQL in pgAdmin4 with port 84?
There is a very good reason this port restriction should be removed.  When using a Platform As A Service (PAAS) that creates endpoints based on services, it is typical to create the service on port 80 or 443 regardless of what is behind the URL.  Since this is just a host name, there is no reason why this should be blocked.  The landscape is different then the data center level as these services could be spun up at any time.  This requirement is arbitrary.