Before changing a remote service, save its configuration and record the commands needed to restore it. Keep an existing management session open until a second connection has succeeded.
Check name resolution, the TCP connection, the TLS handshake, and the application response separately. A successful ping only verifies ICMP reachability; it does not verify a web service.
Certificate renewal needs both an automated schedule and a successful reload of the service using the certificate. Check the certificate served on the network after renewal, not only the file on disk.