How to open iptables port?

Question

iptables

How to open iptables CENTOS 7 port?
My attempts = 0

sudo iptables -F
sudo service iptables save
sudo systemctl restart iptables
sudo systemctl status iptables => OK
sudo iptables -A INPUT -p tcp --dport 1540 -j ACCEPT
sudo iptables -A OUTPUT -p tcp -m tcp --dport 1540 -j ACCEPT
sudo service iptables save
sudo systemctl restart iptables
sudo systemctl status iptables => OK

Then I test from another PC

telnet some.vps.myjino.ru 1540
Trying some.41.135...
telnet: Unable to connect to remote host: No route to host

sudo lsof -i -P -n | grep LISTEN
systemd    1     root   35u  IPv4 510425208      0t0  TCP *:111 (LISTEN)
sshd     376     root    3u  IPv4 510424566      0t0  TCP *:22 (LISTEN)
sshd     376     root    4u  IPv6 510424568      0t0  TCP *:22 (LISTEN)
postgres 400 postgres    3u  IPv6 510428401      0t0  TCP [::1]:5432 (LISTEN)
postgres 400 postgres    4u  IPv4 510428402      0t0  TCP 127.0.0.1:5432 (LISTEN)
ragent   422  usr1cv8   14u  IPv6 510430433      0t0  TCP *:1540 (LISTEN)
ragent   422  usr1cv8   15u  IPv4 510430434      0t0  TCP *:1540 (LISTEN)
rmngr    430  usr1cv8   11u  IPv6 510429526      0t0  TCP *:1541 (LISTEN)
rmngr    430  usr1cv8   12u  IPv4 510429527      0t0  TCP *:1541 (LISTEN)
rphost   525  usr1cv8   14u  IPv6 510430433      0t0  TCP *:1540 (LISTEN)
rphost   525  usr1cv8   15u  IPv4 510430434      0t0  TCP *:1540 (LISTEN)
rphost   525  usr1cv8   16u  IPv6 510431458      0t0  TCP *:1560 (LISTEN)
rphost   525  usr1cv8   17u  IPv4 510431459      0t0  TCP *:1560 (LISTEN)

How to make it work?

Answer 1

The topic is not relevant. After 6 hours I found the cause.
The hoster blocks the iptables function due to the tariff plan.
Gino is a complete wreck

Answer 2

Try this (CentOS has firewalld and you can open ports with it)
Opening TCP port 1540
Saving settings (so that they are not reset after a reboot)
You can check the list of open ports like this
P.s. All of these commands must be executed, of course, on behalf of root