If you want to get an accurate speed test reading, you will need to plug a laptop directly into the router. Testing over WiFi can give lower results than testing directly.

*Note-The only way to fully utilize the maximum available bandwidth is by connecting via a cable direct to the router. This is assuming that your laptop has a 1Gb port (older laptops only have 100Mbs port)
This website will show you how to find out if your device has a 1Gb port 
www.cnet.com/how-to/how-to-find-out-if-my-computer-can-do-gigabit-speed/

Broadband speed can be considered in two parts, the speed delivered to your router and the speed seen on your wifi.

The speed delivered to your router is the rate we take into consideration when determining the speed provided to you. Not necessarily  the speed seen on your WiFi network. We can assist with optimising your wifi network to achieve the best speeds possible.

When a WiFi router detects other devices broadcasting a WiFi signal it will back off its data rate performance to ensure internet packets are delivered and not dropped. When you perform a test it is common for the router to drop back on its data rates and you will see a lower result. This is not always a fault with your connection, it is a mechanism to ensure your internet packets are delivered reliably. This is common when using the 2.4 Ghz radio channel as most wireless devices such as microwaves, baby monitors, video senders etc. use this frequency.