Electric vehicle (EV) charging infrastructure hardware–software solutions and communication protocols have inherent vulnerabilities against cyberattacks. Due to the wide range of back doors and infiltration possibilities, there is an important need for solutions that can maintain critical service continuity during incidents. This study proposes a dynamic capacity sharing method for effective use of the constrained grid capacity between neighboring charging clusters in distribution grids when the communication link between the clusters’ operators and the grid operator is disrupted due to hardware faults or cyberattacks. The performance of the developed solution is thoroughly investigated in a Denial-of-Service cyberattack scenario that may take place at different times of the day in realistic scenarios involving residential demand and stochastic EV charging behavior. The analyses validated the effectiveness of the proposed method in improving the deteriorated service level per charging cluster and better utilization of an overall constrained capacity.