Remote Collector shows in the Sensors page but sends no traffic

The firewall is not configured correctly.

Make sure that firewall(s) between the Guardian and the Remote Collector allows traffic on the TCP/6000 port, with the Remote Collector as Source and the Guardian as the Target.

There is a problem with the certificates.

Check that the certificates have been correctly exchanged between the Guardian and the Remote Collector, i.e., that the certificate at /data/ssl/https_nozomi.crt of a sensor appears listed in /data/ssl/trusted_nozomi.crt of the other sensor, or that the certificate chain has been trusted.

There is a connection error.

Check the /data/log/n2os/n2os_rs.log file of the Remote Collector for connection errors. In particular errors related to certificates are logged with the error code coming directly from the openssl library. Once identified the code it is possible to check for the corresponding explanation at the following page: https://www.openssl.org/docs/man1.1.0/man3/ X509_STORE_CTX_get_error.html

A change has been made, but the n2osrc and n2osrs services have not been restarted.

Make sure to restart n2osrc and n2osrs services every time a change in the config or the certificates is performed.