diff --git a/wgengine/netstack/netstack.go b/wgengine/netstack/netstack.go index 21e330aff..90eeed0ec 100644 --- a/wgengine/netstack/netstack.go +++ b/wgengine/netstack/netstack.go @@ -184,6 +184,17 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi if tcpipErr != nil { return nil, fmt.Errorf("could not enable TCP SACK: %v", tcpipErr) } + if runtime.GOOS == "windows" { + // See https://github.com/tailscale/tailscale/issues/9707 + // Windows w/RACK performs poorly. ACKs do not appear to be handled in a + // timely manner, leading to spurious retransmissions and a reduced + // congestion window. + tcpRecoveryOpt := tcpip.TCPRecovery(0) + tcpipErr = ipstack.SetTransportProtocolOption(tcp.ProtocolNumber, &tcpRecoveryOpt) + if tcpipErr != nil { + return nil, fmt.Errorf("could not disable TCP RACK: %v", tcpipErr) + } + } linkEP := channel.New(512, uint32(tstun.DefaultTUNMTU()), "") if tcpipProblem := ipstack.CreateNIC(nicID, linkEP); tcpipProblem != nil { return nil, fmt.Errorf("could not create netstack NIC: %v", tcpipProblem)