We can't know. You have not provided any system information, no details about the project, error logs and so on.
There is no built-in network render features in AE, so we probably need to see that video you are referring to.
A wild guess though, is that you are trying to render a video file, instead of an image sequence. "Skip Existing Files" only works with sequences. Anyway there is, to my knowledge, no way to make several machines write to the same video file. But you can start the project rendering an image sequence, from multiple computers, to the same network folder, and then use the "Skip Existing Files" feature to prevent overwriting the frames.
Thanks for the replies. The "Skip Exisitng Files" and switching to TIFF solved the issues on some projects. Its strange I can load a project and that will render fine using multiple computers. I can open another and it will find the project on the node computers opens it the closes it straight away and carries on searching. At first I thought it was to do with plugins not being installed on node computers but I have installed them all and still get the same problem.
How do I go about getting the logs to post here please?