cctvnewbie2018

How do I find out what my external IP address is or what the port should be?

Hello everyone! New to these forums and CCTV. I'm not a computer guy either. I had cameras installed three years ago around my house and the guy who did it put on an app on my iphone called CCTV Viewer. Recently, I stopped being able to view my cameras either live or recorded when not on the network. I'm trying everything. I can access the IP address when on the network in my browser but the IP address for offnetwork is not working. Does anyone know how to fix this? Am desperate to solve this problem and I couldn't find any solutions on previous posts. I'm sure it's there and I'm just not searching properly. Any help would be greatly appreciated. Thank you!

My router may have changed