the certificate for our educational domain (eduvinet.de) has recently expired and we decided not to renew it since our hosting provider in Germany (Ionos.de) is demanding a very high price for the annual certificate subscription.
However, now we are facing the following issue. There are other educational websites (state educational servers and schools) which have linked one of our sub-sub-domains using the former "https"-link: "https://www.mallig.eduvinet.de". This link is offering quite popular biology class teaching content which is used by many schools for classroom teaching. This link is now returning the following error "This site can’t provide a secure connection" when the link is called up from one of those external websites (e.g. from this website "https://lernarchiv.bildung.hessen.de/sek/biologie/menschenkunde/stoffwechsel/allgemein/edu_5190.html"). Same error is returned when the https-link is directly entered in the browser.
We tried to modify the ".htaccess" file in the corresponding webserver directory of our provider entering the following code lines in order to force a http-redirect but this is not working. Same error is still returned:
RewriteEngine On
RewriteCond %{HTTPS} on
RewriteRule ^(.*)$ http://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
Can anyone if our issue can still be resolved by adding e.g. different code to the ".htaccess" file? If yes, which code? Or will it never work because we are not willing to renew the expensive SSL-certificate and any https to http redirect will only work with an active certificate?
The Ionos.de provider technical support told us that such a https to http redirect with ".htaccess" will not work. ".htaccess" could only be used with active certificate in case there are issues with the https connection to the website.