Information current as of 09/01/2026.
When Ethernet is fast but Wi-Fi is slow, the wireless link—not usually the internet service—is the most likely bottleneck. Distance, walls, interference, channel congestion, the connected frequency band, device limitations, and competing traffic can all reduce Wi-Fi performance. Test the same device over Ethernet and Wi-Fi, then compare it with another Wi-Fi device to identify whether the issue affects one device or the whole wireless network.
Why Ethernet and Wi-Fi can have different speeds
Ethernet bypasses the wireless radio link. If a direct Ethernet connection works while Wi-Fi is slow or unavailable, the problem is likely associated with the Wi-Fi router or wireless path rather than the internet service itself. Wi-Fi performance also varies with the client device, distance, frequency band, physical barriers, interference, and other bandwidth use.
Use a controlled comparison test
Run several speed tests using the same device and service over Ethernet and Wi-Fi. Repeat the Wi-Fi test close to the router and in the location where performance is poor, keeping the test conditions as similar as possible. Then test another Wi-Fi device. A problem limited to one device points toward that device or its Wi-Fi capability; a problem affecting multiple Wi-Fi devices points toward wireless coverage, interference, congestion, or the router’s wireless path. Comparing results at different locations before and after changes gives you a useful baseline.
Check the main wireless causes
Distance from the router, walls, floors, metal objects, and other obstructions can weaken or degrade Wi-Fi. Nearby Wi-Fi networks can create channel congestion, while household devices operating on similar radio frequencies—including some cordless phones and microwave ovens—can cause interference. Other devices performing high-bandwidth activities can also compete for available bandwidth. Check whether the device is connected to 2.4 GHz or 5 GHz: devices on 2.4 GHz may not reach speeds available on 5 GHz, and older devices may not support newer Wi-Fi standards.
Troubleshooting checklist, in priority order
- Repeat Ethernet and Wi-Fi tests with the same device. 2. Test Wi-Fi close to the router and at the problem location. 3. Compare another Wi-Fi device. 4. Check the connected frequency band and the device’s Wi-Fi capability. 5. Move the router or access point to a central, elevated, unobstructed location. 6. Reduce nearby radio interference and investigate congested channels. 7. Pause or identify high-bandwidth activity on other devices. 8. Restart the modem and router. Where applicable, update router firmware and Wi-Fi drivers. Wireless mesh or repeater hops may also perform below a wired connection, particularly in high-interference conditions.
When to check the router, modem, or ISP
If wired speeds are also below expectations, or the issue affects every connection type, investigate the modem, router, upstream equipment, or ISP rather than treating it as only a Wi-Fi problem. Restarting the modem and router can resolve some connection and slow-performance problems, but recurring issues may require checking the ISP or upstream equipment.