Usually, we could know whether the network adapter is Gigabit Ethernet by the following methods:
The easiest: according to the model number and name of the Ethernet adapter.
The most accurate: according to properties.
Method 1, The name or model of Ethernet adapter
In most cases, its model number or name would be a hint. The following keywords: Gigabit, GBE, 10/100/1000M Gigabit, represent the Gigabit Ethernet adapter. On the contrary, Fast Ethernet, 10/100FE etc. are symbols of a 100M one.
So, how to find the name and model number?
1, (On Windows 10) Right-click on "This PC" on the desktop, choose "Manage" to open Computer Management.
2, One-click on "Device Manager" on the left.
3, Find “Network adapters” in the subdirectory and expand it.
Look, it is shown with "Realtek PCIe Gbe Family Controller", which belongs to gigabit network adapter because the keyword Gbe appeared.
Remarkably, it may also be figured out easily by a third-party tool, for example, Wise Care 365.
However, what should we do when the name was Intel(R) Ethernet Connection I218-LM, which matched no keywords.
In this case, we need the second method below, checking network adapter Properties.
Method 2, Network adapter properties.
1, (On Windows 10) Right-click on "This PC", choose "Manage" to open Computer Management
2, One-click with "Device Manager" on the left
3, In its subdirectory, find "Network adapters" with expanding to locate your Ethernet adapter’s name.
4, Right-click on it, enter "Properties"
5, Under Advanced tab, press on "Speed & Duplex" in Property on the left prior to checking whether there are “1.0 Gbps” or “1000Mbps” under the dropdown menu for Value on the right. The 1.0 Gbps Full Duplex as shown below says this device is a gigabit network adapter.
Why does the network maximum speed on my computer show merely 100Mbps even if I have had a gigabit Ethernet adapter?
Before to explain it, we must know the maximum speed displayed in Ethernet Status is transfer speed between this device and router not the maximum speed of this network adapter.
So, the answer is, since your router doesn’t support a gigabit, it can only be speeded up to maximum 100Mbps. Once the router gets upgraded, its Speed will also follow up.