In today’s interconnected world, Lossy and Low Power Networks (LLNs) have become increasingly prevalent across a wide range of Internet of Things (IoT) applications. As these networks continue to expand and evolve, reliability has emerged as a critical requirement that must be prioritized and addressed. In fact, to function effectively and fulfill their intended purpose, LLNs must be reliable. The reliability of LLNs includes factors such as consistent data delivery and durability. When reliability is compromised, the entire IoT system can be affected, leading to data loss and delayed decision-making. In this paper, we evaluate the performance of the Simple ARQ protocol (SARQ) in LLNs. Through a realistic simulation setup using Contiki motes in the Cooja Simulator, we show that SAQR demonstrates better performance in terms of reliability compared to UDP, as well as improved energy consumption relative to TCP. We analyze the impact of the number of nodes on the performance of SARQ compared to TCP and UDP. We show that SARQ maintains good performance across all configurations, demonstrating reliable packet delivery and efficient energy consumption. Furthermore, SARQ’s performance consistently falls between that of TCP and UDP in terms of Packet Delivery Ratio (PDR) and Energy Consumption (EC), making it a very effective compromise and effective choice in various LLN scenarios.