After enabling the Web proxy some “Windows 7” clients have the network hang, this usually occurs if I change some lock setting in the Proxy or if the client access a banned site. It seems that the connection gets “stuck” and does not return the blocked screen to the client, after that the network of the machine hangs completely, the service dns stops and re-starting a machine for the network services to work again.
@mrmarkuz
The machines were located on Google, I removed and I put the internal DNS of the Nethserver and apparently the problem has been solved. Something similar happened.