i can’t access container in a docker

I am a Linux newbie.

In fact, stackoverflow newbie, too.

There are several services on the Linux server ( centos 7).

nginx, netdata are served by the root account is good and well-working

I started the portainer as a docker container.

$ docker volume create portainer_data
$ docker run -d -p 8000:8000 -p 9000:9000 --name=portainer --restart=always -v /var/run/docker.sock:/var/run/docker.sock -v portainer_data:/data portainer/portainer

I can connect to portainer port ( telnet localhost 9000)

But, when I try to ‘telnet ip 9000’ from an external client PC( same network), it doesn’t connect.

Linux server does not have firewall.

Nginx, netdata, and myapp that are not dockers work fine.

In short,
all other services can be accessed from a Linux server without a firewall,
but Docker’s internal container service is inaccessible.

give me advice, please.

have a good day

Source: StackOverflow