Just remember what Reolink says...
While Reolink cameras are perfectly compatible with Reolink NVRs, it is not recommended to add non-Reolink cameras to Reolink...
support.reolink.com
They are quiet on their specs, so who knows the real capability of that NVR, but like I said in your other thread, do not max the camera out.
For kicks and grins drop the FPS to like 5FPS, bitrate to 1000 and see if that gets it below the bandwidth bottleneck if that is the reason.
The Z12E ONVIF port is 80.