Mac Mini 2011 Ethernet only connects at 100Mbps

[Echa]

I have got Mac Mini 2011 from my friend. It is a used Mac mini. My friend used for few months only. Now the problem here is I cannot connect the Ethernet at 1000Gbits speed. It only connects at 100Mbits. I have changed the cable from Cat 5E and Cat 6. On the Router I have also connected other 2 PCs. Any reason for this kind of network speed?

[Sreedharna]

Due to some limitations I think that the Mac consistently only connects at 100MBits. If you are going to connect at 1000GBits forcefully, then the network connection shows a cable disconnect message and you will lose the connection. To check this issue, you need to bring cables, Mini, and router to the Apple Authorized Service Center. They will check it and find out what is wrong with your configuration and what is not supported. However if the router is communicating only via Windows protocol, then how Mac can handle it?

[Ramanujan]

In my case I use ordinary Cat5e patch cables which I connected from the Mac mini to Netgear Gigabit switch and I can connect reliably at 1Gbps. So it does not matter whether you can the old hardware or the new one, just make sure that the cable you are using is compatible.

Also check in System Preferences > Network> Ethernet>Advanced. There is whether the Ethernet is set to "Auto" or manual Speed = 1000baseT ?

[Purujeet]

If you want only the 100mb speeds, then get at least "CAT 5" (Category 5) or better cable. For better performance you can also get "Cat 5e" and "Cat 6". If you want the Gigabyte speed, then your NIC should support it and also the router. If your use poor or damaged cable or using the incorrect router and system settings, then also it is not possible to get GBPS speed. Using long cable also cause to limited speed.