Q: Incoming email authentication

My incoming email has quit working for my gmail account on my Mac but outgoing is working. iPhone and Macbook Pro, same account, are working fine. When I click open email accounts a "sign in"window pops us asking for email address and then password. Afterward a window pops up saying, "authentication failed / failed to authenticate with google." I have tried  reentering the correct password. The password does work on my other devices. Thank you for your help.

RC