SYN_SENT and Connection not private?

Okay so I was basically running a server on a domain, and this is the first time, but when I logged in on the website, Google Chrome gave me an Error "Your connection is not Private" and I couldn't proceed to next page. So I don't know why but I ran CMD and typed in netstat -ano. And lot's of IPs and stuff came up with "Established" and "Time_wait" etc. Then I scrolled down and saw this:

 TCP    [::1]:58109            [::1]:27275            SYN_SENT        6484
 TCP    [::1]:58110            [::1]:18821            SYN_SENT        6484
 TCP    [::1]:58111            [::1]:7754             SYN_SENT        6484
 TCP    [::1]:58112            [::1]:27275            SYN_SENT        6484
 TCP    [::1]:58113            [::1]:18821            SYN_SENT        6484
 TCP    [::1]:58114            [::1]:7754             SYN_SENT        6484

Now Im not a so called "PRO" when it comes to networking, I've heard a little about SynFlood though, but what could this mean? Could you please tell me the reason for why this is happening and what it is? And how I can prevent this? If it helps we've caught some IPs on our network that is not ours once. Please help thanks.

Edit: The error Chrome gave me was "Your connection is not private, attackers might be trying to steal your information from mc110.ggservers.com (Example password, mails and credit card information)". And I can't proceed because the website is using some kind of HSTS it sais.

Recent Questions...