It sounds like the issue is your router needs to have the port forwarding configured to forward port 81 or port 481 (depending on which you are currently using) to the PC running Blue Iris. DMZ mode opens all ports and sends requests to the device you placed into DMZ mode, which can be assumed is your Blue Iris PC.

Do a search on Port Forwarding for your router device to find out exactly how to configure it. It should be very near the configuration area you set the DMZ at.

Thanks for the information. It is really helpful, and I will look at my AT&T router and the possibility of a VPN. Which VPN solution did you use?

It is two years later and the same issue persists. I too basically got zero help from the BI technical support. It is frustrating, as you can simply go to the Play Store and see all the 1 star ratings saying the exact same thing: poor/no video on the app outside of the LAN while the UI3 interface works fine.

Edit: I just tested, and putting the BI server in DMZ Plus mode does fix the issue. The 5286A router is known to have port forwarding issues that will stop VPNs using IPSEC from working. I bet this same issue is hitting BI. The BI team should investigate what is not getting through the router with the app even if there is port forwarding that is not used with UI3. They can probably fix this issue that is causing so many 1 star reviews.

I just want to (1) thank abollmeyer again, as he/she put me on the right path finally; and (2) pay it forward by letting people following my bread crumbs that I didn't like my BI server in the ATT DMZ, so I, instead, put another router (the LinkSys EA9200) on the network and put it in the DMZ. Then I made the Linksys the gateway for the BI server and port fowarded the BI web service port to the BI server. And voila BI video is available remotely. To recap, the ATT Pace 5268AC has a serious problem port forwarding, but you can put an good router behind the ATT and institute passthrough to the the second router by logically putting it in the DMZ. ATT will NOT filter the stream to the second router like this. You can check by disabling "filter anonymous requests" on Linksys and then ping your second router. Then the second router will properly forward requests to and from the BI server from outside the LAN.

Be sure to set the "internet" settings to what your ATT router is showing, and make sure ATT's DHCP is not assigning the range that the second router is using (usually 192.168.1.1).