> Wi-Fi connection issues
Are you finding Wi-Fi flakey? First, you should check you’ve installed the latest macOS updates. Next, click the Wi-Fi menu bar icon and turn off Wi-Fi, wait a few seconds, then turn it on again. Do this for Bluetooth, too, as AirPlay and Continuity features such as Handoff use it to discover nearby devices. Also try the old trick of restarting both your router and your Mac.
Check whether Wi-Fi is working on other devices. If so, click the Wi-Fi icon in the menu bar, turn off Wi-Fi, open network preferences, click Advanced, then select the network you’re having trouble with. Click the minus button to delete it. Turn Wi-Fi on, then reconnect to network and enter its password.