Network Rendering

Hello, everyone! I am having technical issues in creating my own personal render farm. I have connected two Mac mini computers to a router via Ethernet cables. I set one computer as the client, master, and slave. The second computer is merely a slave. I was successful at connecting the slaves to the master. Under the client, I set my priority to one, my chunks to two, and set my output format to png. I then told the client to render “animation on network.” It successfully dispatched four frames, but within minutes there were errors with these frames. The resulting output was black images. Can anyone identity what in the world is going on? Any advice as to how to correct it? Thank you for your time.

What are the errors?