The available bandwidth headroom makes policy throttling an unsupported explanation. ZDX should be used to test the remaining network hypothesis before changing security or bandwidth controls. Zscaler's Network Intelligence Dashboard summarizes Last Mile ISP and application performance, while user-detail diagnostics provide CloudPath metrics and links to associated ISP incidents. Repeated latency, packet loss, or jitter on the last-mile or ISP portion during reported failures would support a targeted circuit upgrade, routing correction, or provider change. Raising the class maximum cannot fix congestion outside the organization's controlled queue when capacity is already available. Reducing TLS inspection without evidence creates a security blind spot, and prioritizing streaming media would compete with the business application. Option D preserves validated policies while collecting evidence for the infrastructure decision that can prevent recurrence.