This is my first time post on this forum, but yes I know how to use the search feature! 
I been using Plex for years now. Had Plex Pass and just recently upgraded due to my kids being of age to use it on their iPads. Up until now, I never had the need to access my Plex outside of my network.
I have read and watched countless videos, spent countless days trying to figure out how to get this working. It turns green for a second, but then I get the double NAT.
I have AT&T as a service provider (modem 5268AC). I have tried setting up my router (Linksys WRT 1900AC) on the AT*T modem with the DMZPlus way, no luck. I tried the normal port forwarding through the router and then the modem, no luck also.
My plex server is running on a machine with windows 8.1, i turned off the SP1 firewall on their, as well as I think on the LinkSys.
All the media is on a WD EX4, wired into the Linksys router
If anyone have any insight that can guide me and help me get this achieved it will be greatly appreciated.
I’m open to maybe skype help if someone has the time, will of course pay for your time helping. Thanks