Nope , setup should be near identical since the 9303 is running firmware from the previous generation of Connectkey controllers.
There is absolutely no issue on the 3655 with Yahoo when the config is right, but try updating the firmware first from here.
Then if it still doesn't work you need to verify settings.
DNS, Proxy, smtp.mail.yahoo.com, port 587 STARTTLS or 465 SMTPS, and of course user/pass.
And since yahoo accounts have been breached yearly and they keep forcing people to change their associated passwords, make absolutely certain you can login via webmail and update the password on the device.
You will also get login failures if the time on the printer is off by more than 3 minutes, so check that.