The recent increase of wireless devices (i.e., STAtions (STAs)) brings forward an increase of energy consumption. We address the energy consumption issues for STAs in Wireless Mesh Networks (WMNs). One of the available techniques for power-saving is the sleep technique. However, since the common transmission mode from the STA to the server is performed based on end-to-end transmission, this results in increase of energy consumption of the STAs since they cannot enter sleep mode until end-to-end communications are completed. To cope with the issue, we focus on an Access Point equipped with External Storage (APES), which provide end-to-end communication instead of STAs. Using this, STAs can shorten the transmission time and decrease the energy consumption since they communicate with neighboring APES. In this paper, we propose a novel method to select the adequate APES as a proxy server based on the number of STAs and the amount of traffic from STAs. The proposed method effectively transmits data and reduces the energy consumption of the STAs. Moreover, we validate the efficiency of the proposed APES selection method through numerical analysis.