Can Not update Alert email password - Frontview

The addresses look fine, so I don't think that is the issue.

One thing to try is to set it up to use your TWC account, and see if that works.

Never used a TWC account. Something happened with the change in the cable modem and the router. This used to work. I'm fairly certain the modem and TWC are not the issue since this problem is unique to the duo and I have a lot of wired and wireless devices on the network. I think I have port(s?) being blocked by the router, but I don't know what ports the duo is trying to use. That's way above my pay grade. Since the duo should be communicating directly (sending the e-mail) the only firewall is the router, unless Netgear has something on the NAS that I don't understand.

I am thinking the ports might be blocked by TWC and not the router. So trying to send via your TWC account to gmail might work.

No luck on the TWC front. Spent a long time with tech support and they claim that the modem and TWC servers do not block SMTP packets. I'm not 100% convinced but still have to research the NAS and the D-link router. I wonder if the NAS has an outgoing port assignment that I don't see.

The NAS connects to the SMTP server using the port you specify in the configuration. There is no other assignment going on there.

I would get an email client that does SMTP (such as thunderbird) and set that up on a PC to use your gmail account (using the same smtp/pop configuration) - and see if that works. If it also fails, then it is not the NAS.