NetworkManager-l2tp versions 1.2.6 to 1.2.14 use the Libreswan or strongSwan default set of allowed algorithms for phase 1 (Main Mode) and phase 2 (Quick Mode) proposal negotiations. This means VPN servers that are using only legacy ciphers that strongSwan or Libreswan now consider broken will result in a failed connection, unless user specified algorithms to supplement or override the default set