Sometimes you might find you can’t logon to Wi-Fi no matter how many times you try, or check the details.
Take a look at your Mac’s date and time. Is it accurate? Sometimes it slips out a few seconds or minutes. If your Mac is old the time might be completely out, with your Mac thinking it’s the year 2001.
You can adjust the time using System Preferences, and clicking the Date & Time icon. Bear in mind that automatically setting the date and time relies on an Internet connection… which you might not have. If so, set the time manually.
This trick is especially useful for RADIUS-based Wi-Fi login, used in corporate environment or education, and bad system time can also affect logging into HTTPS (secure) websites.
To set the time BEFORE you login, which is sometimes necessary for the aforementioned RADIUS logins, you can use Michael Page’s app that shows a prompt at the login screen.