How to open a UDP port in the Centos 7 firewall, firewalld, using firewall-cmd?

Question

Centos 7 server. Trying to open port 3000 for UDP, nodejs ws websockets. Any ideas? I'm stuck! I've checked a few other SO posts to no avail. Thx, Keith =)

• If is stop the firewall, the udp unicast works fine
• When I start the firewall, websocket connections are getting refused, and I'm getting ERR_CONNECTION_REFUSED
• default zone is public

Port looks to be enabled here:

sh-4.2# firewall-cmd --list-all
public (default, active)
  interfaces: enp3s0
  sources: 
  services: dhcpv6-client ssh
  ports: 3000/udp 8080/tcp
  masquerade: no
  forward-ports: 
  icmp-blocks: 
  rich rules: 

From a Mac on the same network:

Mac> nc -uz 192.168.1.101 3000
Connecion to 192.168.1.101 port 3000 [udp/hbci] succeeded!

• ping to 192.168.1.101 is fine

The only thing I can find that looks fishy is this:

Solution

Had the same issue, fixed it by running:

firewall-cmd --permanent --add-port=3000/udp

And then restarted the firewall service

systemctl restart firewalld

Finally restarted my nodjs app and it now worked as expected