Web server is down Error code 521

But what happened after you did that, because you were definitely not still seeing that Cloudflare error then?

That, and you still have Cloudflare enabled with the orange cloud.

;; ANSWER SECTION:
isciforum.com.  300 IN  A  104.21.23.246
isciforum.com.  300 IN  A  172.67.214.182