IKEV2 two devices can connect but only one can make traffic

[Ettore Tagarelli]

Hello,
I've an Openbsd 6.6 machine with IKEV2. I always used it with only one
client connected and it always worked. Trying to connect with two clients
(behind the same NAT) I found out that the connection seems established but
only one client works.
Can anybody help me? Thanks 😊