Hello Tobias, thanks a lot, that solved the question for me (at least on the server :) ).
Using ASN1 ids iked detects the matching policy. However, it then uses RFC7427 for auth (SIG), but the Windows 10 clients use RSA_SIG. This causes a mismatch and the connection can't be established. (Yet, Windows 10 is lacking support for aforementioned RFC). So, I have to find another way, but thank you very much. Best regards, Alex
