Hello, so this customer of mine has a Windows network with SBS2011 Essentials on the server and W7 64bit on 3 clients.
There was a lag problem for all software on the clients connected with the server, so we tested it all by pinging and there's a heavy loss of packets when you ping the server from any client.
This doesn't happen when clients ping each other: no loss whatsoever.
Also, it doesn't happen if you ping a client from the server, so it's one-way only.
The packet loss seems to be totally random, it won't happen for an hour then start to happen every few minutes.
On average, I'd say about 5% of the packets is lost, but the loss happens in waves, so it's heavily felt on the client machines.
We tried changing switches and cables, disabling all non-essential services on the server but still we couldn't find the cause of this. We used Process Hacker and other tools, but to no avail.
The network is behind a Zyxel firewall, but it shouldn't interfere at all with the LAN.
So can anybody help me diagnose this? Thanks.