Comment 4 for bug 1786261

I am having a similar problem, but I have some additional tidbits:
1) I had the same issue after upgrading from 17.10 to 18.04, but before rebooting
2) I have the same problem if I downgrade all the strongswan/charon packages to 5.5.1-4ubuntu2.2
3) First connection attempt after reboot does not always work
4) "sudo service strongswan restart" has some probability that the next connection attempt will work, but no guarantee