Did you change the name of the server after you installed Qlik Sense?
The error looks like it's something that it does not allow you to distribute the certificates, what I could try to do is:
Disable the firewall and open the Qlik ports
Check if you have any antivirus installed and disable it and redistribute the certificates
Did you changed the postgresql.conf file? when I create a cluster depending on the number of nodes in my environment I must change the max_connections = 100 by default is 100, if you have 6 nodes, you have to change for 600. I also change the listen addresses and I set like this listen_addresses = '*' and in the pg_hba.conf file I change this: host all all 0.0.0.0/0 md5 host all all ::/0 md5