I have the problem since yesterday that I get an error 1105, in the afternoon I moved to a new server with Rsync. Unfortunately, I still get an error 1105 in my forum for certain actions, as an example in the search in the forum. My system administrator cannot reproduce the error because the request does not arrive at the Origin Server.
If everything is and it works switching your nameservers back then your DNS entries at Cloudflare are incorrect as @sdayman stated. When a record is all Cloudflare is doing is DNS, the traffic goes direct to the origin. If the origin works fine with other nameservers then DNS is the only other possble cause that does not involve