Login to the SonicWALL at 192.9.200.254 and go to the manage tab at the top.
Find the network section in the menu section to the left and then interfaces.
Find an open interface in the example above it looks like X12-X16 are open but verify physically on the Sonicwall in the server room.
A new IP scheme will have to be set for this interface, and we have just been increasing by one each time. Centurion Insurance 192.168.100.1 Radio 192.168.102.1 2LMN Engineering 192.168.103.1 Ashley Insurance 192.168.104.1 AFP 192.168.105.1
After setting up the interface, you will need to make DHCP reservations for that interface. You can do that under the Network menu on the left side by finding DHCP server.
You will want to select add dynamic and set the range for something similar to the other ranges. Some start at .2 and some start at .25 depending on if they need any static IP addresses for servers, printers, or other devices.
You will want to set the start range, end range, default gateway, subnet and on the DNS tab add the google DNS servers (8.8.8.8, 4.4.4.4) as they will not have access to our network and DNS servers.
After setting that up you just need to run a cable from that interface port on the SonicWALL to the area in the building the new tenant will be in and connect it to an unmanaged switch. I have been using the Netgear GS324P. If they need WiFi, I have been purchasing TP-Link Archer AX55 AX3000.
You may need to set the DHCP scope on the WiFi AP and set the IP addresses of the computers manually to land within that scope.