Have a mini storage client with cameras on 3 separate buildings each with DVR connected by direct burial cat5e.  One run is pushing the limit length wise, right at 100 meters.  Worked fine for a while  but DVR3 (at the end of the long run) went off line.  thought the cable was damaged, but turns out it's fine.  Here's what's weird.  DVR will flat out not show up at switch in building 2,  However laptop plugged into the cable works great, and sees the other DVR's.  Conversely, if I take laptop up to switch at building 2 it will not see DVR3. No ping, etc. But if I plug direct burial cable directly into laptop, it sees it fine.  I'm at a total loss as to what to do. Have even added a switch at DVR3 location, thinking it might boost the signal a tad. DVR3 was initially just direct connected to buried cable. That seemed to help for a while.  Also replaced the switch at dvr2 but no change.

 

See the enclosed crude drawing.

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