idk what additional infos i can provide
i used another domain and it worked as expected

Are you sure you configured the CNAME correctly?

Please check [vercel domain docs](https://vercel.com/docs/projects/domains) to see if it can help you resolve your issue.

i tried everything and the problem was still there
sadly I don't have the domain that had the problem, so i can't help further more to identify the problem, however here is a description:

I added the domain to vercel, added www.domain and made it redirect to the main domain
then i added the records to the domain
vercel confirmed the domains, ssl certificate created (not sure but i felt that it took longer than usual) however, when i enter with that domain the browser doesn't allow me and it shows some errors relate to ssl
firefox shows me this error: "Error code: PR_END_OF_FILE_ERROR"

i used https://www.sslshopper.com/ssl-checker.html to check the certificate, it showd me that there is a valid certificate

but on the browsers (multiple ones, and in different devices, and networks) i get an error

Hmmm this error is a bit out of my hands, i suggest you contact vercel support, i think that would be the best.