Не удается получить доступ к серверу RStudio в CentOS 7 через браузер

у меня есть x86_64 система работает CentOS 7. у меня есть установлен и настроен R и RStudio Server на нем, но не может получить к нему доступ через http://<server-ip>:8787 так как предложено в документации здесь. Я получаю следующую ошибку Google Chrome:

This site can’t be reached
<server-ip> refused to connect.
Search Google for 206 196 8787
ERR_CONNECTION_REFUSED

Я перепробовал и проверил многие настройки сети, брандмауэра. Однако вроде ничего не работает.

R работает над системой

~$ R
R version 3.4.1 (2017-06-30) -- "Single Candle"
Copyright (C) 2017 The R Foundation for Statistical Computing
Platform: x86_64-redhat-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

  Natural language support but running in an English locale

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> print("I Work")
[1] "I Work"

Сервер RStudio настроен и активен

~$ sudo rstudio-server verify-installation
~$ sudo rstudio-server status
● rstudio-server.service - RStudio Server
   Loaded: loaded (/etc/systemd/system/rstudio-server.service; enabled; vendor preset: disabled)
   Active: active (running) since Sat 2017-10-21 21:33:53 MST; 1s ago
  Process: 8300 ExecStop=/usr/bin/killall -TERM rserver (code=exited, status=0/SUCCESS)
  Process: 8346 ExecStart=/usr/lib/rstudio-server/bin/rserver (code=exited, status=0/SUCCESS)
 Main PID: 8349 (rserver)
   CGroup: /system.slice/rstudio-server.service
           └─8349 /usr/lib/rstudio-server/bin/rserver

Oct 21 21:33:53 localhost.localdomain systemd[1]: Starting RStudio Server...
Oct 21 21:33:53 localhost.localdomain systemd[1]: Started RStudio Server.
~$ sudo rstudio-server restart
rsession: no process found
~$ sudo rstudio-server start
~$ sudo rstudio-server stop
rsession: no process found
~$ sudo rstudio-server start
~$ sudo rstudio-server status
● rstudio-server.service - RStudio Server
   Loaded: loaded (/etc/systemd/system/rstudio-server.service; enabled; vendor preset: disabled)
   Active: active (running) since Sat 2017-10-21 21:34:14 MST; 2s ago
  Process: 8449 ExecStop=/usr/bin/killall -TERM rserver (code=exited, status=0/SUCCESS)
  Process: 8477 ExecStart=/usr/lib/rstudio-server/bin/rserver (code=exited, status=0/SUCCESS)
 Main PID: 8480 (rserver)
   CGroup: /system.slice/rstudio-server.service
           └─8480 /usr/lib/rstudio-server/bin/rserver

Oct 21 21:34:14 localhost.localdomain systemd[1]: Starting RStudio Server...
Oct 21 21:34:14 localhost.localdomain systemd[1]: Started RStudio Server.

Вывод netstat показывает, что порт может слушать

~$ netstat -nat | grep LISTEN
tcp        0      0 0.0.0.0:111             0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:8787            0.0.0.0:*               LISTEN
tcp        0      0 192.168.122.1:53        0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN
tcp6       0      0 :::111                  :::*                    LISTEN
tcp6       0      0 :::22                   :::*                    LISTEN
tcp6       0      0 ::1:631                 :::*                    LISTEN
tcp6       0      0 ::1:25                  :::*                    LISTEN

Брандмауэр сообщает, что порт открыт

~$ sudo ufw allow 8787
~$ sudo ufw status
Status: active

To                         Action      From
--                         ------      ----
SSH                        ALLOW       Anywhere
224.0.0.251 mDNS           ALLOW       Anywhere
8787                       ALLOW       Anywhere
SSH (v6)                   ALLOW       Anywhere (v6)
ff02::fb mDNS              ALLOW       Anywhere (v6)
8787 (v6)                  ALLOW       Anywhere (v6)

вывод systemctl

~$ sudo systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
Active: active (running) since Sat 2017-10-21 20:38:02 MST; 35min ago
Docs: man:firewalld(1)
Main PID: 2987 (firewalld)
CGroup: /system.slice/firewalld.service
        └─2987 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

~$ sudo firewall-cmd --zone=public --add-port=8787/tcp
Warning: ALREADY_ENABLED: '8787:tcp' already in 'public'
success
~$ sudo firewall-cmd --reload
success   
~$ sudo firewall-cmd --zone=public --list-all
public (active)
target: default
icmp-block-inversion: no
interfaces: enp4s0f1
sources:
services: dhcpv6-client ssh
ports: 8787/tcp
protocols:
masquerade: no
forward-ports:
source-ports:
icmp-blocks:
rich rules:

Может ли кто-нибудь помочь мне указать, где я ошибаюсь?

Спасибо.