while using

cluster-announce-ip to the host's public IP in the redis.conf

try creating the cluster also with host's public IP

redis-cli -p 7001 --cluster create <host-ip>:7001 <host-ip>:7002 <host-ip>:7003 <host-ip>:7004 <host-ip>:7005 <host-ip>:7006 --cluster-replicas 1 --cluster-yes