[MikroTik] / RouterOSでWindowsのL2TP/IPSec VPNに接続する

pfs-group=none が肝らしい。

/ip ipsec peer
add address=<VPNServer> name=peer-office
/ip ipsec proposal
add name=proposal-windows pfs-group=none
/interface l2tp-client
add connect-to=<VPNServer> name=l2tp-office password=<Password> user=<UserName>
/ip firewall nat
add action=masquerade chain=srcnat out-interface=l2tp-office
/ip ipsec identity
add peer=peer-office secret=<SharedSecret>
/ip ipsec policy
add dst-address=<VPNServer> peer=peer-office proposal=proposal-windows
/ip route
add dst-address=<OfficeNetwork> gateway=l2tp-office

* 色々端折っているので参考程度に。