@MDByr 

So to start there is a difference between the throughput speeds that are advertised and internet speed.   Throughput is the rate at which clients, like a computer, communicate within the network and with the router.  Internet speed is the rate at which a client communicates outside the network.   Internet speeds are based on several factors.  

• Client distance from the router
• Network congestion
• Network interference, like from other network in the area
• Barriers, such as walls, doors, etc
• EMI, which is electric interference. This is from sources like appliances, microwaves, CFLs, etc.
• Hardware.  Like the network adapter in the client (computer, tablet, etc)  

So although you are not seeing the full 1Gbps on your client you might be getting what is considered good speed for that client.