The M-KUBOS/PYNQ cluster is proposed as an energy efficient computing server for MEC(Multi-Access Edge Computing) which treats various tasks including time-critical jobs at 5G base stations. M-KUBOS boards each of which provides the largest model of Zynq UltraScale+ are connected with high speed serial GTH links and STDM (static time division multiplexing) switches. PYNQ(Python productivity for Zynq), an open-source software platform by Xilinx was introduced so that the multi-Zynq system can be used as a multitenant server. The PYNQ cluster can be programmed by extension of a single PYNQ system, and RESTful APIs are introduced for runtime management of multiple Zynq boards from a remote server. The design examples and evaluation results demonstrate that the M-KUBOS/PYNQ cluster achieved 1.0-17.2 times the performance and 1.75-85.8 times the performance per watt of the recent Ryzen-7 server.