Anya, a network technician at a mid-sized enterprise, is troubleshooting intermittent connectivity and fluctuating latency impacting VoIP calls at a remote branch office. Initial checks of the physical layer, including cable integrity and transceiver diagnostics, revealed no obvious faults. Subsequent investigation into interface error counters at the data link layer also yielded no significant anomalies. Anya then verified routing table accuracy and confirmed the absence of routing loops at the network layer. Despite these efforts, the problem persists, suggesting a more complex underlying cause that is not immediately apparent from standard layer-by-layer checks.\n\nWhat is the most critical next diagnostic step Anya should undertake to effectively isolate the root cause of the persistent connectivity issues?