You can SSH into the unit and use the "vi" editor or you can use a program like WinSCP or any SSH client program.
Enter this command
Once the file is open, press the "Insert" key on the keyboard, or press "i" key, find the line
"dhcpc.1.status=enabled" and change to "dhcpc.1.status=disabled"
"netconf.1.ip=0.0.0.0" and change to "netconf.1.ip=192.168.2.30" (in this example I want to use IP address 192.168.2.30)
"resolv.nameserver.1.ip=0.0.0.0" and change to "resolv.nameserver.1.ip=188.8.131.52" (in this example I'm using Google DNS 184.108.40.206, but you can use any other DNS server)
"route.1.status=disabled" change to "route.1.status=enabled"
And add these lines
"route.1.gateway=192.168.2.1" (in this example my default gateway is 192.168.2.1)
To save the file, hit "Esc",
* then ":wq" [enter]
* "cfgmtd -f /tmp/system.cfg -w "
In case it doesn't work, SSH into your unit and see if your mPort can ping www.google.com, if not, please check your DNS server settings.
If you can ping www.google.com, but your mPort appears as disconnected in your mFi Controller, please check your mPort has right adoption values, you can SSH into your unit, then type "mca-cli", and enter "info", if it shows anything different than your mFi Controller's IP address, please enter the right info using the "set-inform" command.