546 DHCPv6 Client - System Port | Service Name:dhcpv6-client

546 is a System Port. Transport Protocol TCP UDP , 546 Service Name dhcpv6-client, Service Name Description: DHCPv6 Client.

Port	Protocol	Service Name	Description	Source
546	TCP UDP	dhcpv6-client	DHCPv6 Client	IANA
546	TCP UDP		DHCPv6 client,Official	wikipedia
546	TCP UDP	dhcpv6-client	DHCPv6 Client	bekkoame

Port	Service Name	Description
4134	nifty-hmi	NIFTY-Serve HMI protocol
5666		Unassigned
6549	apc-6549	APC 6549
7263		Unassigned
7505		Unassigned
8637		Unassigned
9562		Unassigned
9720		Unassigned
11158		Unassigned
11450		Unassigned

A port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service.

Port numbers are assigned in various ways, based on three ranges: System Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private Ports (49152-65535);

The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users. Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a service contact port is defined. This list specifies the port used by the server process as its contact port. The contact port is sometimes called the "well-known port". To the extent possible, these same port assignments are used with the UDP [RFC768]. The range for well-known ports managed by the IANA is 0-1023.
DYNAMIC AND/OR PRIVATE PORTS Registered Ports are those from 1024 through 49151.
The Dynamic and/or Private Ports are those from 49152 through 65535