Camera shows on DVR but not APP

I have a 32 channel NVR that has 16 cameras plugged into it. You can see them all on the NVR at the monitor, but in the app all of them show but one. That one camera says "network unstable connecting again". It never connects. All of the other cameras work fine on the app except that one. Other people with the app see all the cameras also except that one. Any ideas?