What's up with Google showing me a message:

"Your connection is not private"

when I try to visit Datehookup.com?

It also says that attackers might try to steal my information since my connection is not secure.

The other error code I have is NET::ERR_CERT_DATE_INVALID

Has Datehookup closed down or what is going on?

Yeah my virus scanner shows a encrypted network traffic untrusted certificate and warns me against visiting datehookup.

Just found this topic... it looks like datehookup is not working anymore. I don't get your error message but I do get:

This site can’t be reached
The connection was reset.

I cannot access datehookup.