Hi @gracitymay ,
Perhaps special characters such as ! are not accepted for user IDs or passwords.
Did you try another password without any special characters, just upper and lower case letters and some numbers (see p.21-22 for limits on password length) to see if that worked?
If no good try [https://download.brother.com/welcome/doc002333/mfc7840w_eng_net_a.pdf|resetting] (see p.87) the Network Settings and then reconfiguring it again with passwords that don’t have any special characters in it.