What is(are) your Identity Source(s)?  And how is their health?

There are two eDir Servers connected with LDAPS. How should we verify their health?

On each of those eDir servers, run each of the below, stopping to fix any errors identified before bothering with the next step.   Essentially: Check that the servers are connecting well. Check they all partitions are synchronized within a reasonable time, usually minutes). And make sure there are no stuck obituaries on that server.

ndsrepair -T

ndsrepair -E
   (or alternatively for larger systems:  ndsrepair -E | egrep 'Partition|All'  )

ndsrepair -C -Ad -A

Thank you!

Is it better and more stable to have only one iPrint server that is connected to the LDAPS?

But also I do not understand why we losed both Identity Sources.

Was there an eDir problem that you've now fixed?

As a general rule, having that redundancy is a good thing. I haven't seen an issue with it in this instance, but others with more experience might add their comments on it.

Possible reasons could be other failures,
 - such as server certificates expiring along the way. check that all your OES server certs are valid.
 - Basic communications such as a switch failure, even if intermittent on just that one port. Check the port stats if you can
 - and I'm sure there are many others that do not come to mind right away.

The ndsrepair run on both servers with no errors.

After the first restart, I see the LDAP servers and Printers, but the authentication to iPrint Portal shows "Invalid Credentials" and this error in the iprint_mobile0.log: 

Jun 12, 2023 11:33:16 AM com.novell.service.iprint.auth.AuthServiceUtils getAuthUserInfo
WARNING: Error parsing user details from eDirectory for user: null
Jun 12, 2023 11:33:16 AM com.novell.service.iprint.auth.rest.server.controllers.AuthenticationControllerV2 authenticateUser
SEVERE: Authentication failed

From all the printers I see with my user only one in the iPrint Portal.