Restart an external device on Mac
If you have a network device such as a hub or Wi-Fi router connected to your computer and you’re having problems, you might be able to correct the problem by restarting the device. See the documentation that came with the device if you don’t know how to restart it.
It often helps to wait a few minutes between turning off and restarting the device. Also, wait until it has started up completely before trying to use it again.
If you have multiple devices connected in a “daisy chain” to your computer, it is important to turn off all the devices, then restart them in sequence, beginning with the device furthest from the computer. For example, if you have a DSL or cable modem connected to the internet, a router connected to the modem, and your computer is connected to the router, turn off all of the devices. Wait a few minutes, then restart the modem first. When it has started up completely, restart the router and let it start up completely.
If restarting the devices doesn’t help, try restarting your computer.