Two adapters made this list:

  • ASUS USB-C2500 for most people. It adds a 2.5 Gbps Ethernet port to a laptop or desktop through a USB-A port.
  • ASUS XG-C100C for desktops on a 5 or 10 Gbps network. It’s a PCIe card that runs at every common copper speed up to 10 Gbps.

We haven’t tested these adapters ourselves. We picked them from ASUS’s specifications against the criteria below.

First, check what you already have

Many computers have a 1 Gbps Ethernet port, but some already have 2.5 Gbps. Intel, for example, sells a 2.5 Gbps Ethernet controller for PCs, the I226-V, launched in 2022. Check your computer’s or motherboard’s specifications, or the link speed your operating system reports while connected to a multi-gig port. If you already have 2.5 Gbps and your network tops out there, you don’t need an adapter.

Match the other end and the cable

A wired link runs at the speed of its slowest part: the adapter, the port at the other end and the cable between them. A 10 Gbps card plugged into a 2.5 Gbps router port runs at 2.5 Gbps. If your router has only one multi-gig port, a multi-gig switch lets several devices share it.

Cabling matters more as speed goes up. IEEE’s objectives target 2.5 Gbps over at least 100 m of Cat5e-class cable and 5 Gbps over at least 100 m of Cat6-class cable. For 10 Gbps, the target over Cat6 is at least 55 m. 2.5G, 5G and 10G Ethernet explained goes through the rest.

How the two compare

ASUS lists the USB-C2500 as a USB 3.2 Gen 1 Type-A adapter with one RJ45 port that runs at 100, 1,000 or 2,500 Mbps. If your laptop only has USB-C ports, you’ll need a USB-C to USB-A adapter or hub.

ASUS lists the XG-C100C as a PCIe card that supports 100BASE-TX, 1000BASE-T, 2.5G and 5GBASE-T, and 10GBASE-T. The V1 and V3 versions use a PCIe x4 slot and the V2 an x2 slot. A low-profile bracket is included for small cases.

ASUS’s specification pages don’t list operating-system support for either adapter, so check driver support for your system on ASUS’s support page before buying.

Why this list is short

We only include adapters whose specifications we could confirm on the manufacturer’s own pages. Two met that bar when this page was written; we’ll add a 5 Gbps USB option once one is verified. Prices aren’t listed because they change constantly. Each “Check price on Amazon” button opens an Amazon search for that exact model. For routers with multi-gig ports, see the best routers for multi-gig internet.