The Internet plays a crucial role in modern commerce, facilitating e-commerce sales across various sectors including retail and services. In Tanzania, port cities are pivotal economic hubs with significant internet infrastructure needs. A mixed-methods approach incorporating survey questionnaires, IoT sensors for real-time speed monitoring, and econometric analysis was employed. The sample included 100 businesses across three major ports in Tanzania. Internet speeds were found to be significantly correlated (r = 0.72, p < 0.05) with e-commerce sales volumes, indicating a substantial positive impact on business performance. The findings underscore the critical role of internet infrastructure in enhancing economic activities within Tanzanian port cities. Investment in robust and reliable internet networks is recommended to support continued growth and innovation in e-commerce sectors within these urban centers. internet speeds, e-commerce sales, Tanzanian port cities, econometric analysis