- Screen saver on the server
- Screen saver on the client
- Anti-virus bug (on client or on server)
- Power saving setting on the client or the server, especially hard drive energy saving
- Power saving option on the network card property (on the client or the server)
- A cable that need to be re-plug somewhere
- A bad cable or network equipment (faulty switch/router)
- A Wifi signal that become poor
- A dynamic IP address which is changed by the Telecom provider
- Power failure or a power shortcut on any equipment (server, client, router, bridge)
- Lack of bandwith due to poor Internet connection
We know that it is difficult to locate such event and the "good practice" is to analyze the question step by step.
1) Verify if this is happening just on one PC or any of your PCs. If it is just on PC this isolate the problem and means that the server and the network side are most probably not the cause of the disconnections.
2) If this is happening on several PCs, it can means that the problem is located on the server side or on the network. However it can also be due to a screen saver setting that all users PCs have.
3) Try first to turn off all screen saver and power saving (including the network card property which is a different one).