IPSec VPN client on Ubuntu 17.10

[pax]

I'm trying to setup an IPSec VPN client on Ubuntu 17.10 to connect to pfSense.  We have multiple IPSec clients running from iOS and Android.

From the pfSense side it seems the VPN connection is established.  However, on the Ubuntu client the key error message I see is:

"device added (path: /sys/devices/virtual/net/tun0, iface: tun0): no ifupdown configuration found.

It stops for awhile and then Ubuntu receives a 'ISAKMP_N_R_U_THERE' and the connection is torn down.  with one of the later messages being:

Removing a network device that was not added

While waiting for the RU There message, I can run 'ifconfig tun0' and see an interface - that hasn't been configured.    Once the connection is torn down that interface no longer exists.

I've tried googling and looking for ideas but haven't found anything yet that is relevant..  Any suggestions are greatly appreciated.

Thanks… and Merry Christmas / Happy Holidays!