The low latency offered by 5G mobile network and edge computing paved the way for a new approach to platoon control. Moving the controller to the edge overcomes the scalability issues and the limited radio coverage of the vehicles, typical of traditional distributed platoon controllers based on dedicated short-range communication (DSRC) solutions. However, mobile operators must provide a suitable level of quality of service (QoS), offering good radio coverage, but also preventing congestion at the base station level, to guarantee a low latency control loop for sending motion data to the controller and getting the desired acceleration instruction back from the controller, within a short time. In this paper, we investigate the influence of uplink and downlink network delays on an edge-assisted platooning system. We simulate specific scenarios of network congestion by saturating the physical radio resource of the base station, which leads to an increase in communication latency. Through a simulation campaign, we analyze the performance of the platooning system in terms of target distance preservation and string stability.