I've been experiencing same issue and for me the solution was to change in /etc/NetworkManager/system-connections/MY_CONNECTION from: IPSec secret-flags=1 to: IPSec secret-flags=0
I've been experiencing same issue and for me the solution was to change in /etc/NetworkMan ager/system- connections/ MY_CONNECTION from:
IPSec secret-flags=1
to:
IPSec secret-flags=0