Home Security

I do have an alarm system with glass break protection for my home and out building.  I wanted a security camera and the alarm company wanted $500.00 to install one plus $5.00 a month additional monitoring fee.  That would be fine except it would only protect the house and then only if someone broke in the front of the house.  A burglary could, and probably would, come in from the back and not be seen by the camera at all or someone could break into my out building and not be seen. 
   I ordered two security cameras from Amazon (Anran cameras) and a DVR which was Amcrest. 
  I installed the two cameras and plugged them up and they worked great.  I used by old computer or when I got my new computer so I have a nice, big screen to view by house.  One camera shows my out building and the other my back door. 
  I decided to get a third camera for the front door but wanted one that would give me alerts on my computer and/or my phone so I decided to go with Amcrest.  I also decided to order directly from the manufacture.  I wanted a wireless camera so I didn't have to crawl under the house, drill more holes, and string more cable.  Of course the camera didn't work and the instructions said it recommended using Ethernet cable.  What is the point of having wireless if I have to hook the camera up using Ethernet?  After 10 days I still didn't have the camera working and repeated contacts of customer service resulted in a run around.  I asked for a return slip but never got one.  I finally just gave up and sent the camera back.   
  I then ordered a wired  camera and while awaiting it I crawled under the house and strung the cable.  The wired Amcrest camera came so I plugged it up and nothing.  I asked for a return label, immediately it was provided so I just printed it, boxed up the camera and dropped it at UPS an ordered a third Anran camera.  I ordered it Tuesday and it was delivered today.  I plugged it in and I have a clear color image of my front porch.  Simple. 
  I don't understand why Anran cameras work with an Amcrest DVR but the Amcrest cameras don't. 
  I may never know the answer to that but I did learn not to order direct anymore.  Doing so cost me my leverage in getting service and being able to return the product.