Connect to the web via an IP Failover

[Kados21]

Hello,

Here is my system :
I've Proxmox on the IP IP1 with two containers : B and C. C is a container which contains Plesk. I've configured three Ip Failover to three web space on C : IP2, IP3 and IP4. IP2 is the main one.

My problem is the following :
When connect outside from a website on the second webspace (with IP3), the IP returned is IP2. I would like to have IP 3 !

How can I configure Plesk (or Linux ?) to do that ?

Regards,
Kevin