The app is supposed to run on a local LAN, so all the ip address you add are local ip addresses. For every miner you add, the ip address of that miner is rendered as a hyperlink so you can access your miner's web interface more quickly.
If you are monitoring outside your local LAN e.g. via port forwarding, you won't be able to access the miner's interface. A workaround is to setup a VPN server or connecting to the pc running the #AntminerMonitor e.g. via teamviewer