This paper presents a comprehensive performance analysis of 5G New Radio Band 71 (N71, 600 MHz) deployment across a large-scale, multi-region, multi-vendor Proof-of-Concept network spanning six geographically diverse administrative regions. The study evaluates N71 coverage and throughput performance against co-deployed NR bands (N28, N40, N77/N78) through static drive-test measurements, cluster-level OSS key performance indicators (KPIs), crowdsourced Ookla speed-test data, and 5G Standalone cluster validation. Antenna configuration gain from 2T2R to 4T4R is quantified, device ecosystem maturity and carrier aggregation readiness are assessed from an installed base exceeding 34 million terminals, and multi-vendor layering strategies are described for three equipment vendors (Vendor A, Vendor B, Vendor C). Results demonstrate that N71 provides a 2–3 dB RSRP advantage over N28 outdoors, +7 dB versus mid-band layers, and up to +15 dB in deep-indoor scenarios, with uplink throughput exceeding mid-band by more than 90% in low-coverage conditions. In 5G SA mode with N71+N78 carrier aggregation, peak downlink throughput reaches 878 Mbps (CPE) and 1230 Mbps (flagship smartphone), establishing N71 as a viable SA anchor band for VoNR readiness and nationwide 5G coverage extension.