You can still control in HID mode only with a mixer connected to a computer via a USB cable, and connecting all CDJs, a mixer, with LAN cables.
This setting is introduced on the rekordbox connection guide page 7, but some users seem to not find it, hence we decided to post here as well.
This way, you need to select the Player number of the CDJs manually and not Auto.
For example, if the left CDJ is connected to the CH2 of the mixer, and if you want to control DECK 1, the player number must be No.1.
If the right CDJ is connected to the CH3, and if you want to control DECK 2, the player number must be No.2.
If you want to connect two more CDJs, the player number of the CDJ on the CH1 must be No.3 to control DECK 3. The CDJ on the CH4 must be No.4 to control DECK 4.
This method only works for the CDJ-2000NXS2 and later models.
If you open rekordbox Preferences > Audio > Output channels, you can see how it works and how they are routed.