sunnyPYBURN, my suggestion is use the dynamic (DHCP) mode. It should work fine in your case.
The difference in your case will be — if you use static addresses, you need to configure router (or phone in your case), to use proper IP address range. Somewhere in the setting on your phone app should be something like 'IP address range' or similar, and something like 192.168.1.100-200 (numbers can be different). It means that router will allow all clients (devices which connects to it) addresses in range from 192.168.1.100 till 192.168.1.200, so you'll need to configure each camera config accordingly — which means give addresses to cams in 'correct' router range. Dynamic IP's means the router will automatically give the IP's to cameras, so you'll don't need to worry to give them proper addresses. That's simple explanation.
So, it depends from how you will be using it. For example Brahma app can scan for range of IP's to find all cameras, so it can be dynamically assigned, but Andy_S python app – don't, so you'll need to know exact IP to connect to cam. In some cases one preferable over another.
In your case your you should use dynamic configuration.
p.s.
If you still don't get a success, show us the scripts, I mean, upload the ZIP with your configuration.