Last updated by Sascha Brockel on 17 April 2021
NextCloud in collaboration with CloudFlare is the combination I use, among others. After switching my DNS servers to CloudFlare, I noticed that my NextCloud could still be opened in principle, but no more data was loaded.
What is the problem?
The login input fields and the button had simply disappeared. The register button as well. However, the solution was easy to implement after some research. The problem is solved by the Rocket Loader caused in CloudFlare.
What is Rocket Loader?
However, in conjunction with NextCloud, this apparently breaks the entire feature.
Who does not want to do without the feature, which has the possibility in CloudFlare free of charge a so-called Page Rule to create. This can be created directly in the overview of your website configured by CloudFlare via the Page Rules tab.
There you create a new page rule for Cloudflare. Enter your domain or subdomain and select the Rocket Loader setting and leave the slider on Off. Save the whole thing and you have normal access to your NextCloud again! So you can use the advantages of NextCloud in connection with CloudFlare.
Running NextCloud with CloudFlare is not witchcraft. It only requires a small change in the CloudFlare dashboard and everything works as it should. This way, the Rocket Loader can still be used for other (sub)domains to allow for increased speed. If you have any questions, I am always available in the comments or via the contact form.
Solution Source: Nextcloud Forum