Providing passive bandwidth estimation of a wireless link in a transmission control protocol (TCP) slow start state

A device establishes a wireless link with a user device via a network and selects a time period for a slow start state of the wireless link. The device enters the slow start state after selecting the time period and repeatedly provides a quantity of packets over consecutive time periods to the user device. The device determines a delivery rate for each time period, of the consecutive time periods, based on the quantity of packets provided each time period and determines a maximum delivery rate for the delivery rates of the consecutive time periods. The device determines that the wireless link is at a maximum capacity when a current delivery rate satisfies a threshold rate, based on the maximum delivery rate, after a threshold time period of the consecutive time periods and exits the slow start state based on the wireless link being at the maximum capacity.