no, it’s quite the opposite. TR69 protocol clearly states that every CWMP session is initiated by the CPE, so CPE -> ACS works. In order to perform a immediate action on the CPE, the ACS can issue a Connection Request, wich is a simple HTTP GET at the ConnectionRequestURL (that the CPE sends at any inform/boot/bootstrap…etc event) with the correct ConnectionRequestUsername & password … if this is successful, the CPE will initiate a CWMP session to the ACS asap with the 6 CONNECTION REQUEST event and on that session it will receive all the RPCs that are pending.
This step is not working in your case … BUT, because you set the Inform interval to 3 seconds, you have the impression it works … set the inform interval to 1hour and you will see that it will take up to 1 hour for the CPE to refresh parameters or reboot after you requested it.
The reason it’s not working could be a routing problem or firewall (NAT could also be an issue) between the CPE and the ACS.