The primary cause of your Wi-Fi being slow is usage and interference.
Number of devices
Line usage is a function of how many devices are connected and how much bandwidth they are using up. Remember your line speed (bandwidth) is shared across all devices connected to your router. The more devices you have connected the more your line speed will be shared across them. It's always critical to check that you aren't using the line the the max as this will cause congestion and ultimately connectivity issues.
Wi-Fi Interference
Now this could come in may forms e.g. Walls, Other microwave transmitting devices and even your gate! It's important at all times to ensure you have good signal to your device and also to keep your router away from other microwave transmitting devices. Please keep in mind that even your neighbours Wi-Fi signal could interfere with your speeds. So best to keep your router away. If this is not an option then simply log a ticket with us so that we can change the transmission frequency of your router to try and avoid interference.
You may also find that the one day you are ok and the next your Wi-Fi is slow - This is generally because interference isn't static. It all depends on a snapshot in time and what devices around your router are doing then. You may find that you occassionally need to have the channels changed - this is not uncommon.
Other sources of Wi-Fi interference
ref: https://support.apple.com/en-za/HT201542
These things can cause interference with Wi-Fi networks and Bluetooth devices if they are nearby.
Microwave ovens
Using your microwave oven near your computer, Bluetooth device, or Wi-Fi base station might cause interference.
Direct Satellite Service (DSS)
The coax cable and connectors used with some types of satellite dishes can cause interference. Check the cabling for damage that could cause radio frequency interference (RF leakage). Try replacement cables if you suspect interference.
Power sources
Certain external electrical sources like power lines, electrical railroad tracks, and power stations can cause interference. Avoid locating your AirPort Base Station, AirPort Time Capsule, or Wi-Fi router near power lines in a wall, or near a breaker box.
2.4 GHz or 5 GHz phones
A cordless telephone that operates in the 2.4 GHz or 5 GHz range can cause interference with wireless devices or networks while taking calls.
Wireless RF video
Wireless video transmitters that operate in the 2.4 GHz or 5 GHz bandwidth can cause interference with wireless devices or networks.
Wireless speakers
Wireless audio that operates in the 2.4 GHz or 5 GHz bandwidth can cause interference with other wireless devices or networks.
Certain external monitors and LCD displays
Certain displays can emit harmonic interference, especially in the 2.4GHz band between channels 11 and 14. This interference might be stronger if you're using a notebook computer with the lid closed and have an external monitor connected. Try changing your access point to use 5 GHz or a lower 2.4 GHz channel.
Poorly shielded cabling
External hard drives or other devices with poorly shielded cabling can interfere with your wireless devices. If disconnecting or turning off the device appears to help, try replacing the cable that connects the device to your computer.
Other wireless devices
Other wireless devices that operate in the 2.4 GHz or 5 GHz bandwidth (microwave transmitters, wireless cameras, baby monitors, a neighbor's Wi-Fi device) can cause interference with Wi-Fi or bluetooth connections.
Some devices might not specifically state that they operate in the 2.4 GHz or 5 GHz band. The product's documentation should indicate the bands the device uses to operate. These might be referred to as "Dual Band" or "Wi-Fi" or "Wireless" devices.
