The expansion of the Internet of Things environment has led to an increased need for the implementation of robust network security measures. It is a challenging task to select an appropriate protocol that would provide the crucial mechanisms such as data integrity, encryption, and confidentiality. An essential criterion for evaluating such a protocol, especially for the use of the IoT environment, is its performance, since the introduction of additional security mechanisms inevitably imposes some degree of performance overhead. This paper demonstrates a comparative experimental performance evaluation of the application utilizing the two versions of the DTLS protocol, 1.2 and 1.3. Moreover, during the experiments we compare the two types of Ethernet modules, W5100 and W5500, integrated with the popular STM32 Nucleo board with the RIOT-OS onboard. The results demonstrated that currently the W5500 module and the DTLS 1.2 protocol configuration exhibits superior performance, making it the optimal configuration for use in more demanding IoT environments.