I setup my router to forward port 5900 to my internal computer running VNC Server, but I can't connect. I set up the forward under Settings>Advanced>Port Forward>Custom Application port 5900 & TCP. I turned the switch to ON and checked "ON" next to the custom application. I even put the computer on the DMZ and when I launch VNC Viewer it just sits and doesn't connect.
One issue may be which IP I use. When I go to whatismyip.com and see my public IP or do I use the IP shown on my router's About>Internet Status IPv4 IP address?? This shouldn't be this hard.
You are going to want to go to the IP Address mentioned by whatsmyip for remote connections. For local connections you can use what is displayed by VNC Server. VNC should be able to work without port forwarding for LAN connections.
Note that port forwarding is only available on public IP addresses. VZW broadband devices normally rest behind a NAT firewall which makes all custom port forwarding options irrelevant. The exception are the HomeFusion/4GLTE internet installed routers that supposedly get public IP addresses by default. You have to secure a truly public IP address for your VZW device before remote connections are possible. Otherwise there is no way to even find your personal network devices on the internet, all you would be talking to is the NAT.
Work arounds to NAT are the same as they have always been:
1. Setup a VPN for your two PCs
2. Purchase a public IP from VZW for $500
3. Terminate and switch to a provider that offers public IP addresses
I just went through this long and frustrating exercise, and want to let folks, including the Verizon tech staff know that newer NVR (Net Video Recorder) units are available that support peer to peer (P2P) connections. These will circumvent all of the issues discussed in these questions, and do not require that you obtain a static IP address. If you have no option other than a 4GLTE system to connect to the internet, which is my situation in two remote rural locations that only have Verizon signal and no other, go ahead with the 4GLTE router with voice, and make sure you get an NVR that supports peer to peer connections. These are very easy to set up, and most of the providers' software allows the configuration to be done on your handheld device by scanning a QR code that will appear on a monitor or on the NVR label. I've been very satisfied with my system function using this setup.