Despite considering all the following posts,
 L2TP IPsec VPN client on Ubuntu 14.10  How to connect to L2TP over IPSec VPN?  How to connect to L2TP over IPSec VPN?  l2tp/ipsec problem  Can´t connect VPN using network-manager-l2tp  L2TP/IPsec NetworkManager plugin using only username, password and PSK
I have been unable to set up a connection to my university's VPN.
Although strongswan and network-manager-l2tp are running, and all data (gateway/vpn ip, username, password, pre-shared key, phase1 & phase2 algorithms) are entered, I get the error message that the "Connection failed: Activation of network connection failed."
What am I missing?
126.96.36.199 Main Mode Handshake returned HDR=(CKY-R=e8f536147acee1d4) SA=(Enc=3DES Hash=SHA1 Group=2:modp1024 Auth=PSK LifeType=Seconds LifeDuration=28800) VID=4048b7d56ebce88525e7de7f00d6c2d3c0000000 (IKE Fragmentation)
Thus, I have set the "Advanced Options"-Tab to:
Phase 1 = 3des-sha1-modp1024
Phase 2 = 3des-sha1
[no UDP encapsulation]
Stopping the system xl2tpd in the terminal hasn't helped either.