CPE Wan Management Protocol v1.1

Well I think I found out what port 4567 is supposed to be for:

"2.3.4 Asynchronous ACS Initiated Sessions
An important aspect of service auto-configuration is the ability for the ACS to inform the CPE of a configuration change asynchronously. This allows the auto-configuration mechanism to be used for services that require near-real-time reconfiguration of the CPE. For example, this may be used to provide an end-user with immediate access to a service or feature they have subscribed to, without waiting for the next periodic contact.

The CPE WAN Management Protocol incorporates a mechanism for the ACS to issue a Connection Request to the CPE at any time, instructing it to establish a communication session with the ACS.

While the CPE WAN Management Protocol also allows polling by the CPE in lieu of ACS-initiated connections, the CPE WAN Management Protocol does not rely on polling or establishment of persistent connections from the CPE to provide asynchronous notification.

The basic mechanism defined in the CPE WAN Management Protocol to enable asynchronous ACS initiated communication assumes direct IP addressability of the CPE from the ACS. An alternative mechanism is defined in Annex G, which accommodates CPE operating behind a NAT gateway that are not directly addressable by the ACS."