Encode one port per one ArtPollReply is preferred

[hideakitai]

Currently, four ports are encoded and limited to four ports.

Art-Net devices can send multiple ArtPollReply in order to publish a number of ports greater than 4. The sequence of ArtPollReply is differentiated by the BindIndex. ArtPollReply can encode the information for 4 input ports and 4 output ports; however they must all share the most significant 11-bits of the Port-Address. For this reason, the preferred implementation in Art-Net 4 is to encode only one port per ArtPollReply. If a product has 16 output ports, it will send 16 ArtPollReply using binding.

https://art-net.org.uk/how-it-works/discovery-packets/artpollreply/