C22.02 Agent, build 29051 was successfully installed.
By attempt to register Agent with correct customer credentials, the following errors appear: "Access to the Management Server was denied" or "Registration Timed out"
Manual registration fails with "Access denied. Not allowed for non-privileged users. Domain: AGENT_CORE"
The article describes two issues that have a common cause.
On September 30, 2021, the Let's Encrypt old root certificate [DST Root CA X3] expired.
Let's Encrypt introduced a new root certificate [ISRG Root X1] in advance, but for compatibility with the old devices that don't receive updates anymore they also implemented a cross-signature for the old root certificate [DST Root CA X3].