There are three interfaces on the groov Box, Eth0, Eth1 and the Wlan.
The simplest set up is to connect Eth0 to your network and use that to both access groov and your PAC/PLC/OPC-UA.
If you are running a standard lan, the groov will pick up an IP address and register its host name on the network.
Using groov this way, you do not have to adjust any network settings at all.
If you want to use the Wlan, then you will need to log into groov admin and set up the wireless, the groov user guide has instructions on how to do this.
If you are using groov Server for Windows, then groov will use the PC settings.
In this case, the PC will need to have its own wireless adapter and the settings for such will be configured via Windows.
If you are trying to access groov from outside your LAN, then you will need to use a VPN or set up portforward.
If your ISP uses a dynamic IP address, then you will need to register with a dynamic name server company that your router supports. There are guides on the web for how to log in to your router and check which services are supported, its important to do this before signing up for an account. (Some are free, some have a yearly fee).
I hope this helps get you up and running.