You may refer to the following two methods to get sound output for Reolink NVRs.
Applies to: All Reolink NVRs.
Method 1. Attach the NVR to a monitor/TV (which needs a speaker on the hardware) via the HDMI port. The resolution of the monitor/TV should be 1920*1080, 1080*720, or 4K, or the NVR will not have a sound output if the monitor/TV has another resolution used.
Method 2. Plug a loudspeaker box into the audio out jack at the back of the NVR to get the sound output for the cameras added to the NVR.