High-speed connector simulation usually fails not in the connector model itself, but in the launch and the fixture around it. A few practices that have saved me board spins: First, model the launch, not just the connector. The via field, antipad, and escape routing dominate return loss above 20 GHz. If your model starts at a clean 50-ohm port, you are simulating a connector that does not exist on your board. Second, keep the port setup honest. Wave ports need a long enough uniform section to settle the mode; lumped ports are convenient but hide the launch discontinuity. When the two disagree, trust the wave port and investigate the lumped-port placement, not the other way around. Third, de-embed with a real fixture model. A thru or thru-reflect-line standard built from the same stackup beats an idealized de-embedding every time. Check that the de-embedded S-parameters are passive and causal; non-passive results usually mean the fixture model, not the DUT, is wrong. Fourth, mesh the connector pins, not the whole board. Local mesh refinement around pins and ground vias, with a coarser mesh elsewhere, keeps run time sane without giving up accuracy where the field actually concentrates. Fifth, validate at one frequency before sweeping. Compare simulated and measured insertion loss at a single mid-band point first. If that point is off by more than a dB, a full sweep will only produce a prettier wrong answer. How do you handle connector launches in your EM models — full launch included, or idealized ports?