RHEL 10 must use FIPS 140-3-approved cryptographic algorithms for IP tunnels. GROUP ID: V-281014RULE ID: SV-281014r1165397 Overriding the systemwide cryptographic policy makes the behavior of the Libreswan service violate expectations and makes system configuration more fragmented.
Solution
Configure RHEL 10 so that Libreswan uses the systemwide cryptographic policy. Add the following line to "/etc/ipsec.conf": include /etc/crypto-policies/back-ends/libreswan.config