Make sure to only use wired ethernet for best results.
With wifi you'll see a lot of lag, and with two adapters, it can happen that the players send the info to both adapters, and then you'll get glitchy data.
With your gear, you'd connect the players to the numbered inputs on the mixer, and then connect the mixer's PC connector to either the machine directly, or your network switch.
Also make sure the player index on the players is unique, and that they are connected to the same number port /channel on the mixer.
You can find our Denon guide here: https://resolume.com/support/en/sync-to-denon-players
Are you using SoundSwitch on the same machine?