When you come across such situation where you are allowed to connect multiple computers by using a wireless local area network, no doubt there is some security concerns. On the contrary a wired local area connection ensures more security but surely you will need to bear the cable clutter. If you need not have multiple computers connected by LAN you can use only single connection to the cable modem which ensures security, suggest the computer support experts.
First of all you need to make sure you have got your cable modem installed by your Internet Service Provider. Tech support experts suggest that you need to make sure the Ethernet cable is long enough to reach to the computer from the cable modem.
Now you need to turn off the computer. Then you will need to insert one end of the Ethernet cable into the modem and the other end of the cable into the network adapter of the computer. Once the set up is done, you need to check whether the connection is established. For this, you need to turn on the computer and launch any browser like Internet Explorer or Mozilla to see if the connection is established. If you want more information on these find computer support here.