Getting an "unsupported stream type" error on the recorder for a camera?
This means that the recorder does not support the encoding type on the camera. Check the encoding type the recorder supports (if looking at the data sheet of a recorder, it'll be under 'video compression'), then change the camera to match one of the supported types.
Example: For a DS-7216HGHI-SH, the supported encoding type is only H.264. If any cameras are using any other encoding (like H.265), it'll give you that error.
* screenshot from DS-7216HGHI-SH's data sheet