References: https://gist.github.com/pastleo/aa3a9524664864c505d637b771d079c9 https://askubuntu.com/questions/981165/l2tp-ipsec-failing-to-connect-kubuntu-17-10   When run the command to install the package `networkmanager-l2tp 1.2.10-3`, an error occurs like below: $ yaourt -S networkmanager-l2tp … ==>…