If you perform a speed test to determine your internet connection speed, e.g. with the cnlab UX Test, you should connect your test unit directly by Ethernet cable to the modem of the internet provider. It has turned out that speed loss determined during a measurement by WLAN is often not due to the internet connection as such, but due to the local WLAN connection.
WLAN standards
The maximum data rate indicated in the WLAN standard and on the WLAN component is usually only about half available for the actual data transmission. For the older 802.3b standard, this makes up about 5 Mbit/s, and for 802.11a/g/h it makes up about 25 Mbit/s. Only for 802.11n and 802.11ac will more than 100 Mbit/s be reached.
WLAN standard | Year | Frequency band | Maximum data rate | Typically achievable data rate |
1999 | 5 GHz | 54 Mbit/s | 25 Mbit/s | |
1999 | 2.4 GHz | 11 Mbit/s | 5 Mbit/s | |
2003 | 2.4 GHz | 54 Mbit/s | 25 Mbit/s | |
2003 | 5 GHz | 54 Mbit/s | 25 Mbit/s | |
2009 | 2.4 GHz | 289 Mbit/s (4x4 MIMO technology) | 145 Mbit/s | |
2009 | 5 GHz | 600 Mbit/s (4x4 MIMO technology) | 300 Mbit/s | |
2013 | 5 GHz | 433 Mbit/s (80 MHz channel width) | 250 Mbit/s | |
2013 | 5 GHz | 1299 Mbit/s (3x3 MIMO, 80 MHz channel width) | 650 Mbit/s | |
2019 | 5 GHz | up to 11 Gbit/s (160 MHz channel width) | Mobile/PC - 1Gbit/s | |
| 2020 | 6 GHz |
The WLAN interfaces of modern notebooks, tablets, smartphones and cable network or DSL modems usually support the fast 802.11ac standard. Devices that were taken into operation before 2010 usually have network cards with an 802.11a/g/h standard with a maximum data rate of 54 Mbit/s.
For compatibility reasons, WLAN access points may operate devices with different standards. If any devices with the 802.11b standard, i.e. with the maximum data rate of 11 Mbit/s, are connected to your access point, this may essentially impair the data rate of your fast devices.
WLAN radio channel
For WLAN, note that the maximum available data rate per radio channel will be shared with other WLAN users on the same access point or in the home network. Furthermore it is possible that an access point in the close proximity (e.g. the neighbor's) will work on the same radio channel. If the neighbor's signals in your network are about as strong as your own, the channel capacity will be shared with the neighbor. You can use various programs or mobile apps to get an overview of assignment of the WLAN channels.
If a 2.4 GHz WLAN system also shows strong signals from other access points on the WLAN channel of your access point, set another channel. If the other signals are weaker by 30 dB or more, no channel change is necessary. Some 2.4 GHz systems and all 5 GHz WLAN systems will automatically look for free channels. WLAN systems can be impaired by interferences as well (e.g. radio phones, microwave ovens). A channel change may improve this as well.
WLAN signal and dampening
Finally, observe that WLAN signals will grow weaker as the distance from the access points increases or due to dampening by walls, doors or heat-insulated windows. You may measure good speeds close to the access points and bad ones just a few meters away from it.