As GPU capacity fragments across geographically distributed sites, single-cluster LLM inference routing assumptions break down in measurable ways. We present Solyx AI Grid, a cross-site inference routing control plane that integrates GPU hardware telemetry (DCGM), vLLM application metrics, and real-time WAN signals (RTT, jitter) into per-request placement decisions via a 10-signal weighted pressure scorer. Across two empirical campaigns--six H100/H200 SXM GPUs and nine RTX PRO 6000 Blackwell SE GPUs spanning three US datacenters, eight workload classes, and a 216-cell SLO matrix--Solyx AI Grid delivers 1.56--1.75x throughput at tier-2 SLO over round-robin across all eight classes, cuts capability-mismatch leakage to 0.43% (versus 32% for standard routers), and reroutes around failures at a p99 of 1,247 ms versus 4,226 ms. We further find that GPU hardware telemetry leads application-layer SLO breach by 11.2 seconds on average, enabling proactive traffic drain before user-facing latency impact. To our knowledge, this is the first public empirical study of live physical multi-site LLM inference routing combining hardware telemetry, application metrics, and active WAN path signals.