The Problem

Arma Reforger's Enfusion engine uses server-authoritative vehicle physics. When you call Physics.ApplyImpulseAt() or similar force methods, they execute locally on the calling machine only—they do not replicate. This creates an immediate desync:

• Client applies impulse → vehicle moves to position X
• Server doesn't know about impulse → server thinks vehicle is at position Y
• Server issues correction → client snaps back to Y
• Result: Stutter, jitter, rubberbanding

This affects any mod implementing runtime physics forces: dynamic center of gravity, sling loads, towing, wind effects, external damage impulses, etc.

Root Cause Analysis (From BI Lead Script Developer)

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Key insight from MarioE (Bohemia Interactive lead script developer) on Discord regarding why external physics forces cause multiplayer issues.

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The Physics Solver Problem

From MarioE:

"It's the solver of the Physics. It's a bullet physics thing. If you force set a position, without accounting for anything else, You break what the physics simul is solving. It's reference is now wrecked"

Why Explosions Work But Continuous Forces Don't

Explosions apply a single impulse—the Bullet solver integrates it once and moves on. Both machines receive the same network event, apply the same impulse, done.

Continuous forces (CG effects, sling loads, towing) create frame-by-frame competition:

• Frame 1: You apply impulse, vehicle sim also runs
• Frame 2: Vehicle sim "corrects" toward its calculated state, you apply another impulse
• Frame 3: Repeat...

Server and owner diverge due to network latency. When NwkMoveComponent checks deviation thresholds, it issues corrections → stutter.