I switched the nameservers to cloudflare, than i could browse my domain in HTTP, I than enabled HTTPS on cloudflare and since than my site is not reachable anymore
In your Cloudflare dashboard under SSL/TLS, make sure your encryption mode is set to “Full (strict)”. It looks like it may be set to “Flexible”, which can cause this problem.
It should be “Full (strict)”, not just “Full”. But also, the change should have taken effect immediately. Are you sure the setting is changed? For some reason this part of the Cloudflare dashboard has been made more confusing recently. You should see something like this:
Okay, thanks for verifying that. The problem persists, so this isn’t the cause.
Requests for your domain are redirecting back to themselves. Do you have any Redirect Rules set up in Cloudflare? Do you have any redirects set up (like, to redirect to HTTPS) at your host? Disable any redirects you might have either at Cloudflare or at your host.
Okay, that had an effect. Your server is now returning error 526, which indicates that the SSL certificate on your server is not valid. Now that the redirect is gone, the problem needs to be addressed with your host: you need to have a valid SSL certificate in place there.
In the meantime, you could disable “Always use HTTPS” at Cloudflare, and set your encryption mode to “Off”, and then your site should work, it just won’t have SSL until you address the underlying certificate issue.
I didn’t check into this, i registered the domain on the wrong host, meaning expensive SSL and one told me i can use cloudflare and get the SSL free without the need of buying the expensive SSL certificate with my hoster.