what r the factors that affect connection speeds

The bandwidth, signal, your phone support upto what speed, network type (2g, 3g, 4g). 

In case of desktop it is the service provider, connection bandwidth, connection range, traffic on the website, etc.

The broadband bandwidth or the Signal strength are factors that affect speed.

Internet Traffic, Server speed of the site you are visiting, your computer's Hardware and Software configuration, Traffic on your Home Network are the factors that affect your Internet speed.