dhcp

Unable to connect iMac and iPhone to network, but iPad still connects. Message I get is ‘WiFi has self[assigned IP address..... and will not be ale to connect to the internet .... When I go to the TCP/IP tab, I have clicked on Renew DCHP lease, then the DHCP client ID box is highlighted, but I do not know what that is ... I have tried just clicking OK after Renew DCHP license, but that doesn’t help.

iMac (Late 2013) is on High Sierra, 10.13.6. I have tried this several times, rebooting between attempts. My iPhone SE also won’t connect. Under WiFi, IP is configured automatically, Renew Lease looks like a link, but nothing happens when I select it ... the other option is Cancel.

Is there something I need to update to get the DCHP to work?

Thank you for any help!