Refer to the exhibit.

The decisive message is TS_UNACCEPTABLE, followed by “Traffic selector negotiation failed.” During IKEv2 CHILD_SA creation, the peers negotiate traffic selectors defining the protected local and remote address ranges. RFC 7296 defines TS_UNACCEPTABLE as indicating that the proposed traffic selectors are unacceptable. The displayed encryption, integrity, and PFS parameters do not produce an algorithm-rejection notification; Phase 1 has already completed, and the failure occurs while negotiating selectors for the CHILD_SA. The engineer must make the protected-network definitions complementary on both FTD peers—for example, one peer’s local network must equal the other peer’s remote network, with compatible masks. Changing AES, extending the IKE lifetime, or removing the PFS group does not correct mismatched encryption domains. RFC 7296—IKEv2

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