I can't view video stream in Montage and on single monitor

[bigsub]

Hi to all, I just install zm 1.30.4 on ubuntu server 16.04. I have 5 ip cam as monitor, I can view the video streaming in cycle, in montage review, but don't in Montage and single monitor viewing.
Where could be the problem?
Now my server is inside a private network and I port forwarding zm on port 80, and I'm using a dyn dns. All of the 5 ip camera are connected in zm with local ip addresses.
thanks to all

EDIT: just to try, on a monitor, I put the dyn dns address (and I also port forwarding the 554 port) instead of using local ip address, and now it's all ok.
If is it possibile, I do not want to expose to the internet the 554 port on each ip camera. How can I resolve?
What would happen if my router isn't connected to internet for a while? ZM can still reach every ip cameras?

[bbunge]

Is PATH_ZMS set to /zm/cgi-bin/nph-zms

What instructions did you use to install Zoneminder?

[bigsub]

PATH_ZMS is set correctly.
I followed the official howto
http://zoneminder.readthedocs.io/en/sta ... untu-16-04

Have you an idea about the solution?
Thank
Thanks

[bbunge]

More up to date instructions:
https://wiki.zoneminder.com/Ubuntu_Serv ... e_easy_way

[Baylink]

bbunge: this comes up *a lot*: do we have a poorly chosen default somewhere?

[bigsub]

Hi to all, I think that I resolve the problem. I used ONVIF function in ZM and now, the monitor is ok with local ip address. Using ONVIF add some variables at the end of the monitor's URL (?transportmode=mcast&profile=Profile_1). So now I can view monitor with local ip address.

In this case the ip cam is a Trendnet tv-ip310pi.