NDMP backup error-ndmp_data_connect_v3 failed, status = 23 (NDMP_CONNECT_ERR)

Hi

I am configuring NDMP backups on new NBU servers. The port 10000 is open both ways. The storage array is sun7410. I am setting up a 3 way backup. I have checked with the network team that there is no firewall between array and nbu servers. The credentials are all set. When I try to run the backup, I am getting below error. Any help would be greatly appreciated.

Error ndmpagent (pid=31196) ndmp_data_connect_v3 failed, status = 23 (NDMP_CONNECT_ERR)