If you are converting a generic wifi IP camera to ethernet, it may not be that simple as many are default hard coded to a static IP of 192.168.1.168 and login info admin/admin.
From there you can login to the camera and assign it to DHCP by going to http://192.168.1.168
For security these cameras +DVR should be on a separate untagged VLAN or if possible a physically isolated non-internet connected switch/network.
The reference below is applicable to many of the r........
This is not just a Linux issue but a general issue most software or hardware players cannot play the resulting exported/backed up format of .h264 from DVR security camera footage for some silly reason.
There is a simple solution in Linux using ffmpeg fortunately.
Convert the .h264 file into mp4
ffmpeg -i yourfile.h264 -codec copy video.mp4
play dvr .h264 file........