How to rectify service interruptions after surge testing of data center switches?

Service interruptions after surge testing of data center switches are often caused by misalignment of the response timing of protection devices, such as the TVS turning on before the GDT and absorbing excessive energy, thus burning out. Corrective measures: The GDT was replaced with a 3R090L-6X8 from Etymotic (DC breakdown voltage 90V, current capacity 5kA, response speed <100ns) and isolated from the TVS by a 10Ω/2W resistor in series; the TVS was replaced with a 15KP58CA (VRWM=58V) and a suitable varistor was used to ensure that the TVS did not enter the avalanche zone before the surge voltage reached the GDT breakdown threshold; simultaneously, at least four grounding vias with a grounding copper foil width >3mm were added to the PCB to reduce loop inductance; actual measurements showed that before the rectification, ±4kV surge interruptions occurred 2 times out of 10, and after the rectification, they occurred 0 times out of 10, passing the IEC61000-4-5 Class A rating.