I'm fairly sure it doesn't support SHA-2 and can't use Gmail or Office365.
But make certain you have the absolute latest firmware running from here.
It would be smtp.gmail.com port 465 or 587 and the full email for the login name. But again, I don't think it will work due to the SHA-2 thing.
You could get it running by enabling Less secure apps within the gmail account, and using the aspmx server. But that would only allow emails to be sent to other gmail hosted accounts as that server won't/can't relay.
Best bet is a service like SMTP2Go.