Wired or Wireless Network. A Wired Network is faster and far more secure but it involves running wires. A Wireless Network is sort of easier to configure if you ignore the Security and doesn't need any Wires except the one between the Modem and the WiFi Access Point, the down side is that it's terribly time consuming to correctly configure and slow compared to a wired Network.
With a wired LAN all you need do is feed the output from the Modem to the Uplink Port of a Hub with enough ports for the computers you want to connect and run the CAT5e or 6 Cables to the computers.
If you want a Wireless LAN all you need do is run a CAT5e or 6 lead from the Modem tot he Uplink Port of a WiFi Access Point nd then connect a computer to it with a CAT5 Cable and run the Setup Program for the WiFi Access Point. Remember to change the WiFi Access Points Password and enable the strongest security that it supports. Write down the Password/;PassPhrase for the Security System and then if the Computers in the Office already have WiFi Networking you just need to set these up and include the Password/PassPhrase in the setup. Naturally if the computers do not already have WiFi Capability you need to install WiFi Adapters in them as well.
With a WiFi LAN the Stronger the Security the slower the connection between the computers & Internet is but as Wireless Signals from a WiFi Access Point can travel up to 500 Meters if you do not enable the security anyone within range can steal your Bandwidth and most likely your Data stored on the computers as well.
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