I encountered the question too.

The follow file is the connect file for vm that can connect using remote viewer:

[virt-viewer]

type=vnc

host=192.168.10.41

port=5900

password=rdXQA4zr/UAY

# Password is valid for 120 seconds.

delete-this-file=1

fullscreen=0

title=HostedEngine:%d

toggle-fullscreen=shift+f11

release-cursor=shift+f12

secure-attention=ctrl+alt+end

versions=rhev-win64:2.0-160;rhev-win32:2.0-160;rhel8:7.0-3;rhel7:2.0-6;rhel6:99.0-1

newer-version-url=http://www.ovirt.org/documentation/admin-guide/virt/console-client-resources

[ovirt]

host=ooeng.tltd.com:443

vm-guid=76f99df2-ef79-45d9-8eea-a32b168f9ef3

sso-token=4Up7TfLLBjSuQgPkQvRz3D-fUGZWZg4ynApe2Y7ylkARCFwQWsfEr3dU8FjlK8esctm3Im4tz80mE1DjrNT3XQ

admin=1

ca=-----BEGIN CERTIFICATE-----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\npTs0KJFNgeVnUhKanB29ONy+tmnUmTAgPMaKKw==\n-----END CERTIFICATE-----\n

the firewall list of the host 192.168.10.41 is:

[root@ooengh1 ~]# firewall-cmd --list-all public (active)

target: default

icmp-block-inversion: no

interfaces: bond0 ovirtmgmt

sources:

services: cockpit dhcpv6-client libvirt-tls ovirt-imageio ovirt-vmconsole snmp ssh vdsm

ports: 6900/tcp 22/tcp 6081/udp

protocols:

masquerade: no

forward-ports:

source-ports:

icmp-blocks:

rich rules:

the follow file is the connect file that vm that cannot connect using remote viewer: