My SSL Certificate Sensor - Socket Error # 10049 Cannot assign requested address.

Are there any exposed subdomains on this, other than www? Did you already try to include the SNI name accordingly? Is the DNS name resolved different internally than externally by any chance?

Yes There are subdomains (www) and There are other domains on the server under different IP addresses I included the domain and also tried the subdomain as the SNI DNS resolves the same on the core server as to the world wide web.

When I create a SSL Certificate Sensor on the device, it works properly. Did you by any chance create the Sensor on the probe device, not one with www.aawtrains.com as it's device address?

The site happens to be on the same machine as the prtg core server so it's not really on a remote probe. Do I need to create it on one of my probes so it monitors it from an outside machine?

Usually, creating a new device with www.aawtrains.com as host address should be sufficient. When you ping the address via command line on the server, what's the resolved address?

Same .28 address that is specified in IIS for the bindings...

When I create the same sensor on another probe, it does return a result but it's wrong. It reports 7 days instead of over a year:

Actual SSL cert Expires: Sunday, August 28, 2022

Just to make sure - you'd need to use www.awwtrains.com for the virtual SNI host as well, not just www - at least that seems to be what you're using. I've configured it with the full URL and it shows 622d remaining (thumbprint would be 8193F0DF8BF00526F0518DF04D07670B0A9EC09D).

Can you verify that?