As your server returns an error 444
It doesn’t really matter if the certificate is valid or not.
The “No SNI” case it only for old Browsers who doesn’t use the SNI mecanism.
If you want to block these browsers, it’s fine.
If you prefer to allow them, you should present a valid certificate (and if possible the one of your most visited domain) :
- if the browser wanted to visits a domain present in the certificate, it will works
- if the browser wanted to visits another domain of your server, he will encounter a (probably by-passable error), as with many other websites.
According to https://caniuse.com/#feat=sni 97.4% of visitors have Browsers with SNI support.