I don't know what it is, but often I cannot see some or all computers on my home network. The computers are the following: Laptop, Windows 8.1, wired; Desktop, Windows 7, wired; two tablets, Windows 8.1, both wireless. As far as I know the machines are configured correctly: Private Network discovery and file and printer sharing are on and even Public Network discovery and file and printer sharing are on. I cannot discover any reproducibility in the visibility of the computers. When they are there or not seems to be quite random. What can be wrong and how to solve this?