How do I check if all the needed ports are open for my network server installed in Linux machine

If your network servers is installed in Linux machine,
iptables --list shows what ports are allowed. Make sure all the intended ports are included here.

The below is an example of output on a machine that had Chirpstack installed.

root@ip-172-31-17-202:/home/ubuntu/Variants# iptables --list

Chain INPUT (policy DROP)

target prot opt source destination

ACCEPT tcp -- anywhere anywhere tcp dpt:ssh
ACCEPT tcp -- anywhere anywhere tcp dpt:http
ACCEPT tcp -- anywhere anywhere tcp dpt:https
ACCEPT tcp -- anywhere anywhere tcp dpt:1883
ACCEPT tcp -- anywhere anywhere tcp dpt:1884
ACCEPT tcp -- anywhere anywhere tcp dpt:8083
ACCEPT tcp -- anywhere anywhere tcp dpt:8883
ACCEPT udp -- anywhere anywhere udp dpt:1700
ACCEPT tcp -- anywhere anywhere tcp dpt:3001
ACCEPT tcp -- anywhere anywhere tcp dpt:8886
ACCEPT all -- anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT all -- anywhere anywhere


Chain FORWARD (policy ACCEPT)

target prot opt source destination

Chain OUTPUT (policy ACCEPT)

target prot opt source destination

ACCEPT all -- anywhere anywhere