My iMac Wi-Fi detects internet networks but it doesn't connect to any, but my other PC connects fine to them.
It is a second hand iMac, it worked fine when I set it up, it connected for a day or 2 then no more. It still can detect the network but can't connect. With another PC of mine I can connect fine to the network I'm used to and the same one that the iMac worked with for the first 2 days.
Best Answer
Assuming you've already tried rebooting the iMac, you could try totally removing your Wi-Fi service, restarting your Mac, and adding your Wi-Fi service back again to see if that resolves the issue.
While you don't specify your version of macOS, the steps below should work:
Let me know if this resolves the issue.