This was an odd error that a colleague brought to me while testing automation around the configuration of an NSX Edge.
He had created the Edge successfully, and configured the Load Balancer, but on trying to enable it, it was erroring. When he tried enabling it through the Web Client, the above error was displayed, and the change was automatically reverted.
After a lot of digging, I discovered that the configuration for the Load Balancer had a Pool where the “IP Address / VC Container” object was a Service Group, and one of the members of that Service Group was an IPSet for the CIDR block that NSX was trying to include in the server name.
I’m not sure whether that is even a supported configuration, but I changed it to point to a Service Group that included the members of the target web farm, and the Load Balancer could then be configured successfully.