Error while Adding slave node on Master node

sh@kubeslave:~$ sudo kubeadm join --token cwxswk.hbkuu4jua82o80d1 --discovery-token-ca-cert-hash sha256:ff1b0cfe5aec94f90a42bdb45d2b8bfde34006017c0e3f3026a84388f46a5495
[sudo] password for sh:
[preflight] Running pre-flight checks
error execution phase preflight: couldn’t validate the identity of the API Server: abort connecting to API servers after timeout of 5m0s
Please let me know the way to fix it.