One of the nondeterministic polynomial (NP) hard problem in the area of wireless networks is the quality of service (QoS) routing problem. This has always been a key area wherein research is required to enhance the QoS metrics considered with respect to the considered network model. In this paper, mobile ad hoc network (MANET) model is identified for which an effective QoS routing protocol which meets the set QoS constraints is designed employing the novel variant of differential evolution (DE) model. The ultimate aim of the proposed work is to identify an optimal feasible path for the MANET model with the set objective function criterion being met. A variant of DE capsule net model is built by hybridizing it with the nature-inspired firefly (FF) algorithmic approach. The effectiveness of the proposed technique is achieved by minimizing the set objective function on satisfying the QoS constraints in the MANETs.The developed technique chose better QoS path with respect to the best fitness value than that of the route replay the shortest path algorithm of ad hoc ondemand distance vector (AODV) protocol. The modeled variant DE-FF model achieves better QoS metrics with all the set constrained being met. Simulated results depict the superiority and better performance of the developed DE-FF model than that of the other methods considered for comparison from the existing literature works.