[SOLVED] Should i have SNI when my websites are on different ports in the same ip address?

Should i have SNI when my websites are on different ports in the same ip address?

In trying to understand how all of this works so excuse me if my questions sound kinda obvious or i misunderstand some things.

Let me set up a scenario:

I have a server that has 2 web sites hosted, it runs on Windows server 2019 with IIS 10. For each website, there's 2 parts: A frontend made with Angular, and a data API made with .net 7, with TLS 1.2.

All sites are pointing at the same ip address (1.22.33.44) but with different ports, for example:

www.example1.com => https://1.22.33.44:44374

www.example1DataAPI.com => https://1.22.33.44:44375

www.example2.com => https://1.22.33.44:44376

www.example2DataAPI.com => https://1.22.33.44:44377

Each site has its own SSL certificate, so we need 2 for each full website.

When you go into IIS to edit the bindings of a site there's a check under the host name that says "Require Server Name Indication":

This server doesn't have a "Main" site, in the future there will be atleast 5 more websites made with the same structure as the example above.

My questions are:

Should i leave the "Require Server Name Indication" box checked or unchecked for all the sites in my example?
If not, then in what scenario would it be mandatory to have it checked?
I read that you would have to use it if you have for example 2 sites on a server that point at the same ip address and port. Can someone confirm me if that's correct please?

Solution

According to https://www.cloudflare.com/learning/ssl/what-is-sni/ and https://knowledge.digicert.com/quovadis/ssl-certificates/ssl-general-topics/what-is-sni-server-name-indication ,all three of your problems will be solved after understanding the role of SNI and how it works.

SNI allows the server to safely host multiple SSL Certificates for multiple sites, all under the same IP address and same port. When different websites use different ports, the server can determine which SSL certificates should be used based on the port directly.

Above all, in your example, It doesn't need the SNI. You should use it when multiple sites under the same IP address and port just like the example you gave.