OpenVPN always loads engines available on openssl
OpenVPN uses EVP API and always loads all available engines and tries to use them.
In the case of aesni for AES* the cryptodev engine is slower than openssl userland implementation
glsxb(4) does not support all crypto operations of AES-256 and breaks openvpn.
The improvement is to add a patch to support engine none to disable the loading of the engines.