It is most likely that firewall is blocking these ports in the agent machine.
Could you please check if the port range 35001-35100/tcp is opened for the agent machine to connect from the SVM?
Also make sure that there are no firewalls enabled in the ONTAP side blocking any communication to the agent machine.
Please look into the documentation under "Network Configuration" on how to disable firewall in the agent machine.
https://docs.netapp.com/us-en/cloudinsights/task_cs_add_agent.html#before-you-begin
-Abhi