Abstract: Apparatus and methods are provided for TCP bufferbloat resolution. In one novel aspect, the TCP client monitors a TCP throughput, determines a TCP throughput stability based on a changing rate of the TCP throughput, adjusts a RWND size dynamically based on the determined TCP throughput stability, and sends the dynamically adjusted RWND size to the TCP server for flow control. In one embodiment, the TCP throughput is stable if the changing rate of an increase or decrease of the TCP throughput is smaller than a threshold, otherwise, the TCP throughput is unstable. The TCP client decreases the RWND size if the TCP throughput is stable, otherwise the TCP client increases the RWND size. In one embodiment, the increase of the RWND size uses the default RWND size adjustment method and the decrease of the RWND size is further depending on the increasing or decreasing state of the TCP client.