L2TP too slow

I am only getting around 250 kbps performance on LT2P to a Windows 7 client - painfully slow. I swapped in my old SonicWall TZ170 and I get 2500 kbps (with their GlobalVPN). How to fix this? The VPN is my primary purpose for purchasing this router. Thank you.

- EdgeRouter PoE with v1.9.1

- CPU is only 3%

- ping over VPN shows no packet loss - connection seems stable but slow

- tried rebooting router and Win 7 client

- full configuration attached, with some highlights below:

NOTE: wan is eth4, lan is eth0

vpn {
    ipsec {
        auto-firewall-nat-exclude disable
        ipsec-interfaces {
            interface eth0
            interface eth4
        }
        nat-networks {
            allowed-network 0.0.0.0/0 {
            }
        }
        nat-traversal enable
    }
    l2tp {
        remote-access {
            authentication {
                local-users {
                    username xxx {
                        password xxx
                    }
                }
                mode local
            }
            client-ip-pool {
                start 192.168.168.6
                stop 192.168.168.9
            }
            dhcp-interface eth4
            dns-servers {
                server-1 8.8.8.8
                server-2 8.8.4.4
            }
            ipsec-settings {
                authentication {
                    mode pre-shared-secret
                    pre-shared-secret xxx
                }
                ike-lifetime 3600
            }
            mtu 1300
        }
    }
}