150Mbps is just a theoretical maximum speed of downloading. Normally the actual speed is below that. Actual wireless speeds vary significantly from the above theoretical maximum speeds due to:
• Distance - distance from the access point, as well as any physical obstructions, such as walls, signal-blocking or reflecting materials affect signal propagation and reduce speed.
• Interference - other wireless networks and devices in the same frequency in the same area affect performance
• Shared bandwidth - available bandwidth is shared between all users on the same wireless network.