VPN L2TP/IPSec not working after firmware update. RV345P v1.0.03.27

[ozgrunt]

I recently upgraded the firmware on our RV345P to v1.0.03.27.
As per instructions I did a full reset and a manually input of all settings.

The problem is that VPN L2TP/IPSec on Windows and Cisco IPSec on OSX have stopped working.
On Windows I can make the connection using L2TP/IPSec but cannot access any machines on the LAN.
On OSX using CiscoIPSec I cannot connect.
Everything worked fine with v 1.0.03.24 and it seems I can't downgrade (or can I?)

Anyone else having this problem.

[marce1000]

 - Check or post activity logs from your Windows VPN client, when the problem happens, 

 M.

[Georg Pauwen]

Hello,

could be related to security certificates. For the Windows clients, which VPN client are you using, and are these Windows 10/11 clients ?

Either way, whatever client software you are using, try and uninstall then reinstall that software...

[ozgrunt]

The logs from Event Viewer (I'm using the Windows Built-in VPN) show the connection to L2TP.
That part works fine. It's the IPSec that is broken. Both in Windows and OSX which uses Cisco VPN Client.
The Site to Site connection (IKE?) I'm running works fine.
IPSec Profile for the L2TP/IPSec is attached as well

[Georg Pauwen]

Hello,

delete/remove the VPN connection in Windows, then add it again (see link below). Then reboot the machine and try to connect again...

https://www.tenforums.com/tutorials/90326-remove-vpn-connection-windows-10-a.html

[ozgrunt]

Thanks Georg but it didn't work. It connects fine but I cannot reach the remote LAN.
Even setting up static routes doesn't help.
And on OSX it won't connect at all.