Your client is using openssl-3.0.7 while IPFire is still on openssl-1.1.1r and there is a mismatch between these two openssl versions in terms of the ciphers defined as default.
There has been work on evaluating openssl-3 for IPFire but there have been so many security related reversions or CVE’s with openssl-3 that the decision has been made to hold on any migration to it until the security stability has improved.
See this previous forum thread which covers this topic.
https://community.ipfire.org/t/ovpn-cert-creation-algo/7911