I've just started looking into the network speeds at my office, the entire network is setup to be "Gigabit". This includes Gb switches, Gb Network cards and Cat 5e cabling.

I'm not expecting the full speed, I just want more than ~90 Mb/s.

I've been running some tests with iperf the linux tools and checking the hardware with ethtool. I have 3 servers and when doing my checks/test I discovered that the two backup servers can access each other at around 450 Mb/s but when using either one of them to connect and test the main server, I only get the 90Mb/s even though ethtool shows the networking card running at 1000/Full.

The only difference between all the server/networking cards is the "Port" which ethtool shows. On the two backup servers the "Port" is shown as MII yet on the other it's shown as "Twisted Pair".

When using ethtool -s to manually set the "Port" to MII on the main server, it looses all connectivity and does not show "Speed" or "Duplex".

Anyway, Am i doing something wrong? Is there a specific reason my main server cannot use Gb when there appears to be no difference except the "Port"?