registeredmembers.com does not load at all, because you have no DNS records set up.
As for uhdnews.com, that message comes straight from your server and you possibly block the Cloudflare IP addresses. Make sure that all addresses from IP Ranges have access to your server, check your server logs for that.
Thank Sandro for your kind help. But for UhdNews dot com, I am still confused about your suggestion. What should I do now? Do you have any video for this solution?
You need to check this with your server administrator and make sure the site does not block Cloudflare.
As I mentioned, you best check first the server logs and the server configuration. You can also pause Cloudflare (Overview screen, bottom right). Unfortunately, server administration is beyond the scope of the forum here and better discussed at StackExchange or Reddit.