Cannot access my non-Cox camera system. What is being restricted on my modem and why?

I have a Lorex DVR Camera system.  Connected to the Pano Modem/Router.  Originally, I connect via  the Lorex ECO Stratus app by the Device name (not IP/Domain).  I could connect this way both at home and away.  Never had to switch anything around.  Now, all of the sudden, I have had to use the router's DMZ with that private address inserted.  The to connect, I have to input my Cox public IP into the app for it to connect … but this only works outside of my home network. Been with Cox for 10 yrs.  Had this camera system for nearly 5yrs.  All of the sudden, about 6 weeks ago, I lost the ability to connect while away until I figured out that I needed the DMZ.  I cannot get any senior technician from COX to call me back.  I am an IT pro with the Military and I find this Pano wifi app and cox.com setup to be limiting and insulting to anyone in the IT field.  I just want to control my router the way it should be.  The Pano Wifi won't even update or discover properly.  I.E. Cox changed my public IP a few days ago.  My gateway says the correct address … Pano Wifi app still shows the former IP address.  AND, Cox.com gives me a 408 Error now.  Can't even connect to my router from that garbage. 

Becky. This is the URL.  https://www.cox.com/internet/mywifi.cox##myWifi  Also, cox changed my IP address several days ago.  So, this url won’t let me get in to the modem AND the mywifi app also shows the Old IP address.  Which tells me, that there is virtually no discovery going on that presents accurate info to my account or my app.  Since I had to set up a DMZ to access these cameras, it has not worked since the IP address change to my modem.  I have requested a senior network technician to call me....so, please arrange that for me.  All this back and forth with questions is NOT resolving my problem.  I don’t have 3 weeks to keep doing this.  Thanks for your help.

I just typed a whole reply only to have it not submit. So the skinny is.... not resetting modem again.  It’s a week old.  Didn’t have this issue for the last 5 yrs until about a month ago.  It’s not Lorex, it’s Cox and restrictions you impose on the router.  The gateway and the WiFi app show different IP addresses because there is almost no real discovery process within the WiFi app.