Why Wireless Speeds Always Change

Wi-Fi networks support certain maximum connection speeds (data rates) depending on their configuration. However, the maximum speed of a Wi-Fi connection can automatically change over time due to a feature called dynamic rate scaling.

When a device initially connects to a network over Wi-Fi, its rated speed is calculated according to the connection's current signal quality. If necessary, the connection speed automatically changes over time to maintain a reliable link between the device and the network. This is why you should consider the number of devices that will be connecting to a wireless router.

Dynamic Rate Scaling

For example, an 802.11g wireless device in close proximity to a router will often connect at the maximum data rate of 54 Mbps. This maximum data rate is displayed in the device's wireless configuration screens.

Other 802.11g devices located further away from the router, or with obstructions in between, may connect at lower rates. As these devices move further away from the router, their rated connection speeds are reduced by the scaling algorithm, while devices that are closer can have increased speed ratings (up to the maximum of 54 Mbps).

Wi-Fi devices have their rates scaled in predefined increments. 802.11n has a maximum speed of 300 Mbps, while 802.11ac offers speeds up to 1,000 Mbps (1 Gbps). The newest standard, Wi-Fi 6 (802.11ax), promises maximum speeds up to 10 Gbps.

As an example of rates being scaled in predefined increments, for 802.11g, the data rates automatically adjust from 54 Mbps to lower rates: 48 Mbps/36 Mbps/24 Mbps/18 Mbps/12 Mbps/9Mbps/6 Mbps.

Controlling Dynamic Rate Scaling

If you're wondering why you're connecting at a lower speed, investigate some common culprits. Look at the distance between the device and other Wi-Fi communication endpoints, and see if there's any radio interference in the path of the wireless device. Make sure there are no physical obstructions in the path of the Wi-Fi device and check the power of the device's Wi-Fi radio transmitter/receiver.

Other Reasons for Slow Wi-Fi Connections

Numerous things could contribute to a slow connection, not just dynamic rate scaling. This is especially true if your connection is always slow. If boosting the Wi-Fi signal isn't enough, consider other changes.

For example, the router antenna may be too small or pointed in the wrong direction, or there are too many devices using Wi-Fi at once. If your house is too large for a single router, consider buying a second access point or using a Wi-Fi extender to push the signal further.

The computer may have outdated or incorrect device drivers that are limiting how fast it can download or upload data. Update those drivers to see if that fixes the slow Wi-Fi connection.

Wi-Fi speeds are as fast as what you pay for, and the speed is independent of the hardware used. If you have a router that's capable of 300 Mbps and no other devices connected, but you're still not getting more than 8 Mbps, it's likely due to the fact that you're only paying your ISP for 8 Mbps.