Port-forwarding ip dynamic

[Pollock]

Hi. I have to connect to a remote LAN, which is a PLC using a PC with the development of the PLC, to be able to remotely make changes to the program of the PLC.

now, the development environment to connect to the remote LAN, it asks me to enter the public ip of the network, but that is dynamic. I can not use the DynDNS hostname of the remote network, it asks me the ip number and I can not write a hostname. Moreover, I doubt that is NOT true that the ip of the remote network does not change as long as there is a connection in progress, and that means that if I do say, at a given moment the ip of the remote network and write in the development connect remotely, I can also connect, but when you least expect me to change the ip and I remain screwed.

I was told that some routers support a feature that allows me to specify, instead of the remote LAN IP, the ip side of the router's remote (that is NOT one of the LAN where the PLC), and forward connect to the remote LAN, being able to insert in this case the DynDNS hostname. What is this? why can not I find it on my (may not even be that the media ...)

[Kerwin]

if the ip changes you will never be able to make a stable connection

to know the ip from the logical name (dynamic dns) do a simple ping from dos

[Otto]

Sorry, but you're talking about public or private IP?

[Pollock]

Am just concerned about the public IP..

[Otto]

but if the IP changes, the connection drops, regardless of that function on the router that I did not understand what purpose serves out of this..