Need help, cannot connect MacOSX built in client via L2TP

[allitsolutions]

when first installed Softether VPN Server to Windows Server 2012 R2, it worked well.

Windows clients are connecting successfully using the Softether Windows Client.
MacOSX was connected via inbuilt VPN client no problem

Unfortunately macOSX users are not able to connect ?

Error message from the macOSX is "VPN Connection, The L2TP-VPN Server did not respond. Try reconnecting. If the problem continues, verify your settings and contact your Administrator.

I have tried the dynamic DNS and fixed external IP address i have and both have same result.


the log file i obtained from the macOSX computer.

'vpn9999999999.softether.net' (xxx.xxx.xxx.xxx)...
Fri Aug 21 12:49:43 2020 : IPSec connection started
Fri Aug 21 12:49:43 2020 : IPSec phase 1 client started
Fri Aug 21 12:49:43 2020 : IPSec connection failed

Please help