You should not need to use DMZ for the streaming bridge IP (unless you want the streaming bridge to be unprotected on the internet) if you are port forwarding properly to the “static” internal IP address of the streaming bridge. (Notice: assign a static LAN IP to the streaming bridge on the DHCP server of your router is key for this to work properly and everytime you turn on the streaming bridge).
Here are some sites to use for help with port forwarding depending on your router (for any port you want accessible from the Internet including the Streaming Bridge). Use port forwarding with caution as you are bypassing your router firewall protection doing this.
To help you configure your router for port forwarding (large list of router manufacturers):
The port you will need to open is the standard RTMP port for any streaming server which is port 1935 TCP only!
If you have more than one streaming bridge, you will have to port forward additional TCP ports at the router (assuming you do not have access to multiple public IP addresses on your Internet connection) and make sure to assign a static LAN IP address for every Streaming bridge on your router and to configure each Streaming Bridge to listen to the TCP port you are forwarding to it.
Make sure you have the streaming bridge on and running before using the next site.
To test to see if the port is available on the Internet use:
Use 1935 and if you did everything correctly, the site will let you know.
Success: I can see your service on XXX.XXX.XXX.XXX on port ( 1935 )
Keep in mind all of the security risks involved with opening ports.
BTW, network experience in use here, no streaming bridge tested or owned as I can build the streaming server to do the same thing.