First, don't explicitly set the send / receive buffers of the sockets, i.e. remove the default values for network.tcp.send_buffer_size and network.tcp.receive_buffer_size and let the OS control that unless explicitly set.

Second, netty uses a "user space" receive buffer, with adaptive size from 1k to 64k. Allow to control that using transport.netty.receive_predictor_size (for transport) and http.netty.receive_predictor_size (for http) (min / max can be set instead of size, though fixed size is preferable). Also, change that default value to 512k, as 64k is too small.