This is just a small report of my late experiences.
After a long time I visited the demo site of i-MSCP, where you can log in as admin, reseller or user. Every 2nd or 3rd page couldn't be delivered. Cloudflare gave some information that s. th. went wrong, I should try a few minutes later. Then the page appeared. But still every now and than cloudflare came in between with its error message. The demo site itself seemed to operate correct.
Just mention that, because I wanted to lead other people to i-MSCP and don't want them to drive away disappointed by reasons not in the responsibility of i-MSCP. Having a demo site is best to argument for our panel.
Well, after all, this still could have been a regional/local problem or one of cloudflare not being connected good enough to my provider (vodafone).