Ubiquiti UniFi setup(test):

UniFi Security Gateway(USG) + Cloud Key(UC-CK):

1. Reset USG. Default IP: 192.168.1.1, DHCP enabled.

2. Set Cloud Key to DHCP.

3. Connect USG WAN port to local LAN, set IP manually(DHCP not working sometimes).
    Use a switch to connect the USG LAN port, the Cloud Key and a PC.