Although you have the ftpClient rule already enabled, what you could do, to see if the ESXi firewall is your issue.

~ # esxcli network firewall set -e false

This disables the firewall entirely so this won't come in the way. If this doesn't work, try basic troubleshooting from the ESXi host. Do a ping, and see if the routes are correct (esxcli network ip route ipv4 list).

If disabling the firewall resolves your issue, be sure to enable it again:

~ # esxcli network firewall set -e false

And post the output of esxcli network firewall ruleset list and cat /etc/vmware/firewall/*.xml.