If your connection to an agent fails, following are the steps that you need to follow
a) First, check billing for the respected server whether it is active or suspended.
b) check cdp-agent status on the client-server by using command /etc/init.d/cdp-agent status.
If it is not running then start the cdp-agent by using /etc/init.d/cdp-agent start and then Test the connection for the policy on the backup server.
c) If the cdp-agent status is running on the server then kindly allow our backup server IP and port in the csf and iptables on the client-server.
We hope that you might have got an idea regarding the steps to follow in case of agent failure. If you still face queries, feel free to initiate a live chat with our technical team.