@AnnaA
Hello, thanks for asking.
Below is a setup video for your reference to install your wireless router:
https://www.tp-link.com/support/setup-video/
But if you still failed, please refer to the troubleshooting suggestions below to check your settings:
https://www.tp-link.com/support/faq/1556/
Just to confirm, who is your ISP? If the old router is working, you may try with the below steps to see if you can build up the connection on the C7:
1. Unplug the modem’s power cord and unscrew the coaxial cable (if it is a cable modem)
2. Connect the modem to the Router’s WAN port and make sure the Router is powered on
3. Plug the power cord for the modem back in, but leave the coaxial cable disconnected.
4. Wait 3-5 minutes and reconnect the coaxial cable.
5. Wait for modem to reconnect and then check for IP and service.
I hope this helps.