FIPv4Address is defined in IPv4Address.h, which is included from Networking.h, but you may find it easier to use FInternetAddr exclusively. You can conveniently set the IP address with the SetIp function that takes a string as a parameter and avoid the dependency on FIPv4Address entirely. You may need to add an #include for IPAddress.h, which defines FInternetAddr.
If you’re still getting errors, please post a specific error so we can better diagnose it.
Also, you should be able to use just the filename in your #include paths. The full path (starting at the Runtime directory) should be unnecessary if the corresponding module is declared as a dependency, which in your case it appears to be.