L2TP/IPSEC second connection not working

[lavoiekeven]

I got the L2TP connection setuped on 2 differents workstation (Windows 10) with different L2TP user.

Each of the workstation VPN work perfectly alone but if I try to connected both, the second connection always fail.

When I check at Status->Ipsec, i can see that the second connection status become to ESTABLISHED but it finish by being dropped.

Any ideas.