Short answer: a wired connection runs at the speed of its slowest link. To get more than 1 Gbps to a device, the modem or fiber terminal, the router’s internet and LAN ports, any switch, the cable and the device’s own port all have to support multi-gig speeds. For 2.5 Gbps, the cable you already have is very likely fine.
The speeds and the standards
Multi-gig Ethernet fills the gap between ordinary gigabit and 10 Gbps. IEEE 802.3bz, approved on 22 September 2016, defines 2.5 and 5 Gb/s Ethernet over twisted-pair cabling. The aim, as the Ethernet Alliance’s NBASE-T group puts it, was to push the installed base of Cat5e and Cat6 cable, designed for 1 Gbps at up to 100 m, well beyond that limit. 10 Gb/s over twisted pair, known as 10GBASE-T, is an older and more demanding standard.
What matters at home is which cable each speed needs. The IEEE project objectives set these targets:
- 2.5 Gb/s: up to at least 100 m on Category 5e cabling.
- 5 Gb/s: up to at least 100 m on Category 6, and up to 100 m on Category 5e in defined use cases.
- 10 Gb/s: at least 55 m to 100 m on Category 6, and at least 100 m on higher-grade Class F cabling.
| Speed | Cat5e | Cat6 | Higher grade |
|---|---|---|---|
| 1 Gb/s | Yes | Yes | Yes |
| 2.5 Gb/s | Up to 100 m | Yes | Yes |
| 5 Gb/s | Up to 100 m (defined cases) | Up to 100 m | Yes |
| 10 Gb/s | Not targeted | 55-100 m | 100 m (Class F) |
The slowest link sets the speed
Multi-gig ports don’t replace your old equipment; they negotiate with it. Ports supporting these speeds can auto-negotiate the best common rate, falling back to 1 Gbps or 100 Mbps when the other end is older. That’s convenient, but it also means one gigabit device or port anywhere in the path quietly caps the whole connection at 1 Gbps.
Check each link
- The modem or fiber terminal. Its Ethernet port must be faster than 1 Gbps. If you’re unsure where the modem ends and the router begins, see modem vs router.
- The router’s internet (WAN) port. gFiber, for example, recommends a 1 Gbps WAN port for its 1 Gig plan and a 10 Gbps WAN port for its multi-gig plans.
- The router’s LAN ports. Routers differ in how many fast ports they have. ASUS lists its RT-BE88U with a 10 Gbps WAN/LAN port, a 10 Gbps SFP+ port and several 2.5 Gbps ports, for instance. Plug your fastest devices into the fastest ports, or add a multi-gig switch.
- The cable. Match it to the speed using the table above.
- The device. Some computers have 2.5 Gb/s Ethernet built in; Intel’s I226-V controller, which runs at up to 2.5 Gb/s, is one example of the chips used. If yours only has a gigabit port, that’s its limit.
Where Wi-Fi fits
Wi-Fi can be fast, but a single device rarely matches a multi-gig wired link. Intel rates its two-stream Wi-Fi 7 laptop adapter at up to 5.8 Gbps, and only with 320 MHz channels and 4096-QAM, conditions that need the device close to the router. Real-world Wi-Fi speeds are lower, so wired multi-gig devices are where a fast plan shows most. See Wi-Fi 7 explained and Wi-Fi 6 vs Wi-Fi 6E.
If you use mesh, the same rule applies between units: a multi-gig cable between them avoids a Wi-Fi bottleneck, as covered in mesh backhaul explained. For routers whose ports match multi-gig plans, see the best routers for multi-gig internet.