After an ESXi host reboot, the host becomes unresponsive on previously configured network ports, which were modified from the ESXi firewall settings.
Any changes made to the firewall ruleset are not retained after ESXi host reboot.
esxcli network firewall ruleset list
Example: esxcli network firewall ruleset list
Name Enabled
----------------------------- -------
sshServer true
sshClient false
nfsClient false
nfs41Client false
dhcp true
dns true
snmp true
ntpClient true
esxcli network firewall ruleset set --enabled=true -r <rulename>
Example: esxcli network firewall ruleset set --enabled=true -r dns
For more information regarding configuring firwall settings on ESXi host 7.0 and above, please refer article: ESXi Firewall Configuration