This applies when you are trying to configure a custom domain for your status page using Cloudflare DNS. First make sure you created the correct DNS records as indicated by updown, and if you changed them but updown keeps showing the previous value, keep in mind we have to honor the TTL (Time To Live) specified in your DNS, so you may have to simply wait in that case.
status.mydomain.com redirected you too many times
The reason might be that you're using the "Flexible" TLS mode of cloudflare which encrypts on the client side (browser) while connecting to the backend server (updown) using plain HTTP. This would cause a redirection to HTTPS on updown side, which would be ignored by cloudflare and thus causing an infinite redirection loop (that's in the SSL/TLS section):
If you can, use any of the Full mode instead. But of course you shouldn't change that if your backend requires this configuration (e.g. only supports HTTP) because this setting is global as far as we know so changing this will impact you know domain. Continue reading for another simpler option.
The simplest fix for almost any problems related to Cloudflare proxying is to simply disable Cloudflare proxying (the "orange cloud") in your DNS settings, so that the CNAME is really pointing to updown servers directly and you eliminate any kind of CloudFlare induce incompatibility: