1) Load balancer.
2) To have enable two networks adapters simultaneously (Ethernet Local Area Network, Wired Network - Wireless Network)
Normally, the load balancer authorize base on source IP. If end user are using two network adapters both at same time, since the Wifi signal, the network might switch one to another.
In other words, the source IP is changed, so load balancer dispatch the request to other node. the display is redirecting to logon page.