Hi Linc,
Have tried other Macs but same result.
I just tried to connect to the local IP address, it looks like it gets a lot further but still fails.
Here is the last part log on client:
3/09/15 10:41:39.008 am racoon[10864]: 1 times of 92 bytes message will be sent to 192.168.1.10[500]
3/09/15 10:41:39.008 am racoon[10864]: sendto Information delete.
3/09/15 10:41:39.008 am racoon[10864]: IKE Packet: transmit success. (Information message).
3/09/15 10:41:39.008 am racoon[10864]: IV freed
3/09/15 10:41:39.008 am racoon[10864]: IKEv1 Information-Notice: transmit success. (Delete ISAKMP-SA).
3/09/15 10:41:39.008 am racoon[10864]: ISAKMP-SA expired 192.168.1.20[500]-192.168.1.10[500] spi:34147bd2b406996b:f7904e3b3bb52787
3/09/15 10:41:39.009 am racoon[10864]: ****** state changed to: Phase 1 expired
3/09/15 10:41:39.009 am racoon[10864]: no ph1bind replacement found. NULL ph1.
3/09/15 10:41:39.009 am racoon[10864]: vpncontrol_close_comm.
3/09/15 10:41:39.009 am racoon[10864]: ==== Got usr1 signal - re-parsing configuration.
3/09/15 10:41:39.009 am racoon[10864]: ==== flush negotiating sessions.
3/09/15 10:41:39.009 am racoon[10864]: flushing ph2 handles: ignore_estab_or_assert 1...
3/09/15 10:41:39.009 am racoon[10864]: Flushing Phase 1 handles: ignore_estab_or_assert 1...
3/09/15 10:41:39.009 am racoon[10864]: already stopped ike_session_stopped_by_controller.
3/09/15 10:41:39.009 am racoon[10864]: IV freed
3/09/15 10:41:39.010 am racoon[10864]: ===== parsing configuration
3/09/15 10:41:39.010 am racoon[10864]: reading configuration file /etc/racoon/racoon.conf
3/09/15 10:41:39.010 am racoon[10864]: lifetime = 60
3/09/15 10:41:39.010 am racoon[10864]: lifebyte = 0
3/09/15 10:41:39.010 am racoon[10864]: encklen=0
3/09/15 10:41:39.010 am racoon[10864]: p:1 t:1
(Video) Fix: L2TP Connection Attempt Failed Because The Security Layer Encountered a Processing Error3/09/15 10:41:39.010 am racoon[10864]: 3DES-CBC(5)
3/09/15 10:41:39.010 am racoon[10864]: SHA(2)
3/09/15 10:41:39.010 am racoon[10864]: 1024-bit MODP group(2)
3/09/15 10:41:39.010 am racoon[10864]: pre-shared key(1)
3/09/15 10:41:39.011 am racoon[10864]: hmac(modp1024)
3/09/15 10:41:39.011 am racoon[10864]: filename: /var/run/racoon/*.conf
3/09/15 10:41:39.011 am racoon[10864]: glob found no matches for path "/var/run/racoon/*.conf"
3/09/15 10:41:39.011 am racoon[10864]: parse succeeded.
3/09/15 10:41:39.011 am racoon[10864]: caught rtm:2, need update interface address list
3/09/15 10:41:39.012 am racoon[10864]: configuring default isakmp port.
3/09/15 10:41:39.012 am racoon[10864]: 12 addrs are configured successfully
3/09/15 10:41:39.013 am racoon[10864]: SADB delete message: proto-id 3
3/09/15 10:41:39.013 am racoon[10864]: src: 192.168.1.20[52444]
3/09/15 10:41:39.013 am racoon[10864]: dst: 192.168.1.10[1701]
3/09/15 10:41:39.013 am racoon[10864]: SADB delete message: proto-id 3
3/09/15 10:41:39.013 am racoon[10864]: src: 192.168.1.10[1701]
3/09/15 10:41:39.013 am racoon[10864]: dst: 192.168.1.20[52444]
3/09/15 10:41:39.013 am racoon[10864]: SADB delete message: proto-id 3
3/09/15 10:41:39.013 am racoon[10864]: src: 192.168.1.20[52444]
3/09/15 10:41:39.013 am racoon[10864]: dst: 192.168.1.10[1701]
3/09/15 10:41:39.013 am racoon[10864]: SADB delete message: proto-id 3
3/09/15 10:41:39.014 am racoon[10864]: src: 192.168.1.10[1701]
3/09/15 10:41:39.014 am racoon[10864]: dst: 192.168.1.20[52444]
3/09/15 10:41:39.014 am racoon[10864]: pfkey DELETE failed: No such file or directory
3/09/15 10:41:39.197 am UserNotificationCenter[10878]: *** WARNING: Method userSpaceScaleFactor in class NSWindow is deprecated on 10.7 and later. It should not be used in new applications. Use convertRectToBacking: instead.
(Video) Windows 10 connecting to an L2TP VPN Server that is behind a NAT3/09/15 10:41:42.013 am racoon[10864]: performing auto exit
3/09/15 10:41:42.013 am racoon[10864]: Flushing Phase 1 handles: ignore_estab_or_assert 0...
3/09/15 10:41:42.013 am racoon[10864]: vpncontrol_close.
3/09/15 10:41:42.013 am racoon[10864]: racoon shutdown
Sever VPN log shows it assigning the client an IP address but the client hangs up?
#Start-Date: 2015-09-03 09:56:57 NZST
#Fields: date time s-comment
2015-09-03 09:56:57 NZST Loading plugin /System/Library/Extensions/L2TP.ppp
2015-09-03 09:56:57 NZST Listening for connections...
2015-09-03 09:57:27 NZST Incoming call... Address given to client = 192.168.1.50
2015-09-03 09:57:27 NZST --> Client with address = 192.168.1.50 has hungup
2015-09-03 09:57:27 NZST Incoming call... Address given to client = 192.168.1.51
2015-09-03 09:57:27 NZST --> Client with address = 192.168.1.51 has hungup
2015-09-03 09:57:29 NZST Incoming call... Address given to client = 192.168.1.52
2015-09-03 09:57:29 NZST --> Client with address = 192.168.1.52 has hungup
2015-09-03 09:57:34 NZST Incoming call... Address given to client = 192.168.1.53
2015-09-03 09:57:34 NZST --> Client with address = 192.168.1.53 has hungup
2015-09-03 09:57:38 NZST Incoming call... Address given to client = 192.168.1.54
2015-09-03 09:57:38 NZST --> Client with address = 192.168.1.54 has hungup
2015-09-03 09:57:42 NZST Incoming call... Address given to client = 192.168.1.50
2015-09-03 09:57:42 NZST --> Client with address = 192.168.1.50 has hungup
2015-09-03 09:57:46 NZST Incoming call... Address given to client = 192.168.1.51
2015-09-03 09:57:46 NZST --> Client with address = 192.168.1.51 has hungup
2015-09-03 10:04:27 NZST Incoming call... Address given to client = 192.168.1.55
2015-09-03 10:04:27 NZST --> Client with address = 192.168.1.55 has hungup
(Video) Fix VPN not Working in Windows 10 - A Connection to the Remote Computer Could not be Established2015-09-03 10:05:47 NZST Incoming call... Address given to client = 192.168.1.56
2015-09-03 10:05:47 NZST --> Client with address = 192.168.1.56 has hungup
2015-09-03 10:06:26 NZST Incoming call... Address given to client = 192.168.1.57
2015-09-03 10:06:26 NZST --> Client with address = 192.168.1.57 has hungup
2015-09-03 10:12:55 NZST Incoming call... Address given to client = 192.168.1.58
2015-09-03 10:12:55 NZST --> Client with address = 192.168.1.58 has hungup
2015-09-03 10:16:26 NZST Incoming call... Address given to client = 192.168.1.59
2015-09-03 10:16:26 NZST --> Client with address = 192.168.1.59 has hungup
2015-09-03 10:25:07 NZST Incoming call... Address given to client = 192.168.1.55
2015-09-03 10:25:07 NZST --> Client with address = 192.168.1.55 has hungup
2015-09-03 10:33:33 NZST Incoming call... Address given to client = 192.168.1.52
2015-09-03 10:33:33 NZST --> Client with address = 192.168.1.52 has hungup
2015-09-03 10:33:34 NZST Incoming call... Address given to client = 192.168.1.53
2015-09-03 10:33:34 NZST --> Client with address = 192.168.1.53 has hungup
2015-09-03 10:33:36 NZST Incoming call... Address given to client = 192.168.1.54
2015-09-03 10:33:36 NZST --> Client with address = 192.168.1.54 has hungup
2015-09-03 10:33:40 NZST Incoming call... Address given to client = 192.168.1.50
2015-09-03 10:33:40 NZST --> Client with address = 192.168.1.50 has hungup
2015-09-03 10:33:44 NZST Incoming call... Address given to client = 192.168.1.51
2015-09-03 10:33:44 NZST --> Client with address = 192.168.1.51 has hungup
2015-09-03 10:33:48 NZST Incoming call... Address given to client = 192.168.1.52
2015-09-03 10:33:48 NZST --> Client with address = 192.168.1.52 has hungup
2015-09-03 10:33:52 NZST Incoming call... Address given to client = 192.168.1.53
2015-09-03 10:33:52 NZST --> Client with address = 192.168.1.53 has hungup
2015-09-03 10:37:47 NZST Incoming call... Address given to client = 192.168.1.54
(Video) How To Fix The L2TP Connection Attempt Failed | Windows 10, Windows 112015-09-03 10:37:47 NZST --> Client with address = 192.168.1.54 has hungup
2015-09-03 10:37:48 NZST Incoming call... Address given to client = 192.168.1.50
2015-09-03 10:37:48 NZST --> Client with address = 192.168.1.50 has hungup
2015-09-03 10:37:50 NZST Incoming call... Address given to client = 192.168.1.51
2015-09-03 10:37:50 NZST --> Client with address = 192.168.1.51 has hungup
2015-09-03 10:37:54 NZST Incoming call... Address given to client = 192.168.1.52
2015-09-03 10:37:54 NZST --> Client with address = 192.168.1.52 has hungup
2015-09-03 10:37:58 NZST Incoming call... Address given to client = 192.168.1.53
2015-09-03 10:37:58 NZST --> Client with address = 192.168.1.53 has hungup
2015-09-03 10:38:02 NZST Incoming call... Address given to client = 192.168.1.54
2015-09-03 10:38:02 NZST --> Client with address = 192.168.1.54 has hungup
2015-09-03 10:38:06 NZST Incoming call... Address given to client = 192.168.1.50
2015-09-03 10:38:06 NZST --> Client with address = 192.168.1.50 has hungup
2015-09-03 10:41:20 NZST Incoming call... Address given to client = 192.168.1.51
2015-09-03 10:41:20 NZST --> Client with address = 192.168.1.51 has hungup
2015-09-03 10:41:21 NZST Incoming call... Address given to client = 192.168.1.52
2015-09-03 10:41:21 NZST --> Client with address = 192.168.1.52 has hungup
2015-09-03 10:41:23 NZST Incoming call... Address given to client = 192.168.1.53
2015-09-03 10:41:23 NZST --> Client with address = 192.168.1.53 has hungup
2015-09-03 10:41:27 NZST Incoming call... Address given to client = 192.168.1.54
2015-09-03 10:41:27 NZST --> Client with address = 192.168.1.54 has hungup
2015-09-03 10:41:31 NZST Incoming call... Address given to client = 192.168.1.50
2015-09-03 10:41:31 NZST --> Client with address = 192.168.1.50 has hungup
2015-09-03 10:41:35 NZST Incoming call... Address given to client = 192.168.1.51
2015-09-03 10:41:35 NZST --> Client with address = 192.168.1.51 has hungup
(Video) The L2TP Connection Attempt Failed Because the Security Layer Encountered a Processing Error [FIX]2015-09-03 10:41:39 NZST Incoming call... Address given to client = 192.168.1.52
2015-09-03 10:41:39 NZST --> Client with address = 192.168.1.52 has hungup