Hi there and welcome
What we need to do is first disconnect the printer from the old network
To do this
Press Menu on the printer.
Press up or down arrow and choose Network. Then press OK.
Press up or down arrow and choose Network Reset. Then press OK.
Press 1 two times for Yes to confirm the changes.
Then connect the printer to the new network
On your Brother printer, press the Menu, press the up and down arrows to choose Network, and Press OK to proceed.
Press up or down arrow keys to choose Setup Wizard and press OK.
When Enable WLAN? is displayed, press OK to proceed.
This will start wireless setup wizard and the printer will search for available wireless networks. When it displays a list of available networks, choose your desired network and press OK to proceed.
Enter the password (network key) and press Use right and left arrow keys to enter lowercase, uppercase, and numbers.
Once done and connected then attempt again to print to it
Let me know the results please.