Reliable wireless communication is crucial for the interconnected manufacturing systems of Industry 4.0. However, the dense distribution of stations (STAs) and obstacles such as concrete walls and machinery can adversely affect radio performance. Our study investigates the performance of Legacy Wi-Fi and Wi-Fi 6 in a factory through simulations. A ray-tracing-based propagation model is used to account for the challenging radio environment. Based on this, we apply Access Point (AP) grouping strategies to assign the constrained Wi-Fi spectrum in the factory. Multiple traffic types are simulated within the digital twin factory model to evaluate the key performance indicators (KPIs). Our findings show that Wi-Fi 6 significantly reduces Round Trip Time (RTT) compared to Legacy Wi-Fi, though increased bandwidth can lead to higher co-channel interference. The analysis also indicates the difficulty of optimizing Wi-Fi performance in industrial scenarios due to the multiplicity of influencing factors and the complexity of their correlation.