Iam logout again and again

my web login logout again n again when iam active cloudflare dns when i stop this then its working well if iam on cloudflare my admin account offline after 5sec

What’s your Cache Level?
Do you have any Page Rules set up?

It’s also possible that there is some session stickiness to the IP used when logging in. When you connect to your host, you will see a different Cloudflare IPs in your logs. This IP can change at every single request made.
I had the same issue with Plesk.

How to set cloudflare ips