I've done this to originally test my remote cams. You need a PC at the remote location to get it set up. A tool like IP Camera can find and display all the cams internal IP address'. You will also use the cam software to install the cam and set the user and password. After you have that, you can sign into the router, Port Forwarding, and set up a port forward for each cam. I.E. xx.xx.xx.xx:8091. At that point you find the external IP address by going to something like
https://www.iplocation.net/find-ip-address or just search for find my IP and it will show it to you. When you are at home, go into
Blue Iris and add a cam. It will ask for the IP, the port and user & Password. At that time, you can open the cam on your home screen.
This will use a lot of bandwidth depending on how many cams you are accessing. Recording a lot of cams 24/7 remotely may dramatically slow down your net activity depending on your provider.