According to Amcrest both cameras are ONVIF. But that do not work?
There is already a template for Amcrest IP3M-943 using rtsp for high res. video. That camera do not have audio and no PTZ.
Amcrest IP2M 841 is with PTZ and audio and therefore it would be great if it works with onvif. If not, use the same template as earlier to get the rtsp stream which now should include video and audio, but not PTZ.
2 weeks ago Amcrest 943 was solved How connect to Amcrest IP3M-943
EDIT: For Amcrest IP2M 841 make sure you have the latest firmware in the camera.
-Henrik