The most common reason for slow internet at night are scheduled tasks of your PC or consumer electronics. Most of the tasks, like updates for the Windows operating system, are scheduled to run outside the working hours.
Due to the peak overall internet usage at night, this will immediately effect your own internet bandwidth.

The evening between 7pm and 9pm is known as the Internet Rush Hour, when most of the people in your country are using the Internet.

During that time period you are sharing directly or indirectly your internet bandwidth with other people. This lowers the overall throughput of your internet connection.

Categories: Performance