Why is the webserver on port 8080 not visible from the outside?

Question

linux

The situation is as follows:
There is an OpenWRT router with a configured firewall, it forwards a web page to the lighttpd of the router itself, external port 80 , internal port 8081 - it works.
Raised a home server under Ubuntu 15.04 and apache2 on port 80 . External forwarded as 8080 , when you try to switch, it transfers to the router's web server.
However, Plex, which hangs on port 32400 , works fine.
I think that the problem may be on the Apache side.
Please share your tips.

Answer 1

You can look in tcpdump on port 8080
And you can use netcat (nc): hang it on 8080 port tcp and turn on echo.
From another machine, telnet open host:port and look at the nc output
. If empty, then look at what tcpdump shows.
If both there and empty, then 100% router.