Hosts in a Network Load Balancing (NLB) cluster are configured to load balance network traffic. Host configuration is set by using NLB Manager, and if it is not configured properly, the NLB cluster may not function correctly.
Upgrade all hosts in the NLB cluster
A Network Load Balancing (NLB) cluster operating in a mixed mode (where hosts have different versions of an operating system installed) is only supported during rolling upgrades. Until all hosts are upgraded to the latest operating system version, newer NLB features will not be available. You should upgrade all hosts to the latest operating system version.