Getting an ERR_SSL_PROTOCOL_ERROR without a VPN but enabling a VPN fixing it, that doesn’t make any sense to me. The error means that there is some problem establishing the SSL connection, and using a VPN should not resolve that.
Unless some ISPs in your country do something REALLY strange and mangle SSL connections, I cannot explain this behavior.
While also being SSL related, this is a completely different issue.
WordPress ships a file at wp-includes/certificaets/ca-bundle.crt which it uses to verify SSL certificates. However, this file is missing from your website. The way to fix this is to download a fresh copy of WordPress, find the missing file and upload it to your site.
In case more files that this one may be missing, this guide may be helpful: