Basic Fixes:

• Disable and Enable Wi-Fi: You can start by rebooting your Mac first. Once done, you can also disable Wi-Fi from the Mac Control Center and enable it after some time.
• Restart Router: If your home or office Wi-Fi doesn’t show up on all your smart devices, your router can be the main culprit here. A simple restart should fix the issue.
• Update Router Firmware: An outdated router firmware can also put a damper on an otherwise productive day. That said, note that the steps to update router firmware differ from one OEM to another. You can visit your router company’s official website to learn the steps.
• Confirm an Outage With ISP: If your local internet service provider is facing a server-side outage, you may have issues finding a Wi-Fi network on a Mac. You can head to Downdetector and search for your ISP.

Note: The steps above apply to Intel-based Macs. On M-series Macs, the system resets PRAM when it detects the need to do so.  

Fix 2: Clear Network-Related Plist Files

When our office Wi-Fi network failed to show up on a Mac, deleting the network-related plist files worked like a charm. Here’s how you can do so,

Step 1: Disable Wi-Fi on your Mac. Once done, launch Finder and press the Shift Command G keys. Enter the following path.

/Library/Preferences/SystemConfiguration/

Step 2: Find the following network-related files.

• com.apple.airport.preferences.plist
• com.apple.network.identification.plist
• com.apple.wifi.message-tracer.plist
• NetworkInterfaces.plist
• preferences.plist

Once you locate them, right-click and move them to Bin. Right-click on Bin to empty it, and reboot your Mac.

The system will generate relevant files during the system startup. This should cause the nearby Wi-Fi network to appear on your Mac.

Fix 3: Clear Bogus Files on Mac

Step 1: Open Finder on Mac and press the Command Shift G keys. Type the following path.

~/Library/Caches

Step 2: Select items you want to delete and move them to trash.

You can also use third-party applications like CleanMyMac X to clear the app cache on your Mac.