VMware Cloud Director 10.x
VMware Cloud Director is attempting to validate the next hops for the static routes before adding the IP address by reviewing the subnets for all uplinks on the device. When reviewing the additional interface added outside of VMware Cloud Director, it is unable to parse the entry into a valid network and fails with the error indicated. Manually editing NSX objects created and maintained by vCD can create unexpected behavior and is not recommended.
Starting in VMware Cloud Director 10.4.1, external networks can be added to the edge gateway. To correct this behavior, it is recommended to configure the networks via VMware Cloud Director instead of directly in NSX.
In order to work around the issue, the static routes can be removed from the interface to exclude it from consideration during the IP assignment process.