Connect your Mac to the internet using a cable modem
Before you begin, make sure you have your account information from your ISP. See Information you need to connect to the internet.
After you have your information, connect your cable modem to your computer’s Ethernet port, turn the modem on, then follow these instructions to enter the information in Network preferences.
If your computer doesn’t have an Ethernet port, try using a USB to Ethernet adapter or a Thunderbolt to Gigabit Ethernet Adapter.
On your Mac, choose Apple menu > System Preferences, then click Network.
Select Ethernet in the list at the left.
Click the Configure IPv4 pop-up menu, then choose one of the following:
DHCP: Choose this if you receive your IP address automatically from your service provider.
Using DHCP with manual address: Choose this if your ISP uses a DHCP server but provides you with a specific IP address.
Using BootP: Choose this if your ISP provides IP addresses using the bootstrap protocol (BootP).
Manually: Choose this if your ISP gave you a specific IP address and other information, such as a subnet mask and router address. Enter the information you received into the fields.
If your ISP provided the DNS server address and the search domains, click Advanced, then click DNS and enter them in the fields.
Enter any additional information you may have received from your ISP, such as a proxy server address, or special Ethernet information.