This article presents results of approbation of developed model of piece-wise regular fiber optic link, operating in a few-mode regime, with series-connected couple of special multimode optical crypto-fibers “encryptor-decoder”. Unlike the previously developed solution, the model was modified with an ability to take into account influence of fiber optic connector end-face contamination on laser-excited optical signal launching conditions. We present comparison results of computed optical pulse response envelops, distorted during propagation over 10GBase-LX network fiber optic links, containing optical crypto-fibers, depending on various conditions of transceiver laser source connector ferrule end-face contamination.