Loadbalancer + cPanel/WHM always error 404

i have 2 droplet, 1 domain + cloudflare, 1 loadbalancer Droplet A with IP 111.111.111.111 Droplet B with IP 222.222.222.222 Loadbalancer with IP 333.333.333.333 Domain name abc.com

when i acces my domain abc.com i always get error 404, but if i point the domain to my droplet, i can access it without any error. am i missing something?

here is what i do.

Part 1 => Result in 404 (i turn off droplet B) abc.com => A 333.333.333.333 WHN in droplet A setting => current address of abc.com 111.111.111.111

Part 2 => Result in 404 (i turn off droplet B) abc.com => A 333.333.333.333 WHN in droplet A setting => current address of abc.com 333.333.333.333

Part 3 => Result in 200 OK (i turn off droplet B and ofc i didn’t use LB) abc.com => A 111.111.111.111 WHN in droplet A setting => current address of abc.com 111.111.111.111

Part 4 => Result in 404 OK (i turn off droplet B and ofc i didn’t use LB) abc.com => A 111.111.111.111 WHN in droplet A setting => current address of abc.com 333.333.333.333

i’ve tried many setting, but still don’t know what is the cause. please help, thx