Hi and Welcome. My Name is ***** ***** I look forward to assisting you today with your question.
You need to reconnect the printer to your WiFi network and add it as a new printer on your Mac.
For this you need to know your WiFi Network and password.
Press Menu on the control panel of the Brother printer.
Choose Network by pressing Up or Down and press OK
Choose WLAN and press OK
Choose Setup Wizard
If asked to enable WLAN, press 1
It will list your WiFi networks. Select your WiFi network, press OK and enter password ***** connect.
Once you are connected to your WiFi network, then on Mac, go to System Preferences > Printers and Scanners. Delete the old entries of printer by selecting them and clicking the - (minus) button on the left bottom. Then click the + button and add your printer.
If you have any difficulty on following the steps above, please let me know and I will continue to help you