How can I determine an appropriate pod CIDR value for a Kubernetes cluster?
Regarding CIDR (Classless Inter-Domain Routing): That is just a notation to define the subnet / range of IP addresses that you want to use in your network.
If you want to use /16, you must be planning the creation of a fairly big Kubernetes cluster since that will give you >65k virtual IP addresses (Note that we are talking about the SDN / Virtual network, i.e., the IPs you will set for your kubernetes PODs, not your actual nodes / hosts).Here is a CIDR table you can use as reference to decide a more suitable range:https://kb.wisc.edu/ns/page.php?id=3493
Now, in terms of your failure that depends on the CNI (Container Networking Interface) plugin you are using in your Kubernetes cluster. If you are using the default one that must be Kubenet, which has limitations.More information here:https://kubernetes.io/docs/concepts/extend-kubernetes/compute-storage-net/network-plugins/and here:https://chrislovecnm.com/kubernetes/cni/choosing-a-cni-provider/
I hope that helps.