With the rapid development and spread of computer networks and information technologies, researchers are faced with new complex challenges of both applied and theoretical nature in investigating the reliability and availability of communication networks and data transmission systems. In the current paper, we perform the system-level reliability analysis for a redundant system with arbitrary distributions of uptime and repair time of its elements using a simulation approach. Also, we obtained the values of the relative recovery speed at which the desired level of reliability is achieved, presented dependency plots of the probability of system uptime and plots of the uniform difference of the obtained simulation results against the relative speed of recovery; also plots of the empirical distribution function F∗(x) and reliability function R∗(x) relative to the reliability assessment. Software implementation of simulation algorithms was carried out on the basis of the R language. © 2020, Springer Nature Switzerland AG.