How to get notified when internal server/website goes down

So I have a website running from a server. And whenever the server goes down for some reason, the website goes down together. And I have to keep checking the URL to see if the website is still on. Is there a way to get notified when the website goes down?

For example, my website is running at http://10.10.100.6:5000 (I'm logged into 10.10.100.6 in this case). I cannot use online tools because I use a VPN to connect to the server after authentication.

How can I get notified if my website goes down?