Shiny-server installation: Server not responding on port 3838 - r

Question

I installed the shiny-server on a Ubuntu 16.04.1 and according to the console output it is active and running:
systemctl status shiny-server
● shiny-server.service - ShinyServer
Loaded: loaded (/etc/systemd/system/shiny-server.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2016-08-24 18:17:09 CEST; 15h ago
Process: 13175 ExecStartPost=/bin/sleep 3 (code=exited, status=0/SUCCESS)
Main PID: 13179 (shiny-server)
Tasks: 7
Memory: 28.5M
CPU: 158ms
CGroup: /system.slice/shiny-server.service
├─13174 /bin/bash -c /opt/shiny-server/bin/shiny-server --pidfile=/var/run/shiny-server.p
└─13179 /opt/shiny-server/ext/node/bin/shiny-server /opt/shiny-server/lib/main.js --pidfi
lines 1-11/11 (END)
Then I opened the port 3838 as stated in the installation guide:
netstat -ntlp | grep LISTEN
(Not all processes could be identified, non-owned process info
will not be shown, you would have to be root to see it all.)
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN -
tcp 0 0 0.0.0.0:3838 0.0.0.0:* LISTEN -
tcp6 0 0 :::80 :::* LISTEN -
tcp6 0 0 :::22 :::* LISTEN -
sudo ufw status
Status: active
To Action From
-- ------ ----
22/tcp ALLOW Anywhere
3838/tcp ALLOW Anywhere
80/tcp ALLOW Anywhere
22/tcp (v6) ALLOW Anywhere (v6)
3838/tcp (v6) ALLOW Anywhere (v6)
80/tcp (v6) ALLOW Anywhere (v6)
Howevever if I try to access my server over the port 3838 in a browser, I don't get any response from the server and the site stays blank and eventually times out.
Any ideas what I might be missing?

Answer 1

Apparently there was some problem with the port 3838 on my server. Although the console output above states that it is open and listed as "LISTEN", it still didn't work. When I changed the default port for my shiny-server in the configuration file (/etc/shiny-server/shiny-server.conf) to 80, it suddently worked:
# Define a top-level server which will listen on a port
server {
# Instruct this server to listen on port 3838
listen 80;
...