RNG not working as expected

RNG.swift

struct RNG: RandomNumberGenerator {
    let modulus: UInt64 = 233_280
    let multiplier: UInt64 = 9301
    let increment: UInt64 = 49297
    var seed: UInt64 = 0

    mutating func next() -> UInt64 {
        seed = (seed * multiplier + increment) % modulus
        return seed
    }
}

var rng = RNG(seed: 1000)
var numbers = [0, 1, 2, 3, 4, 5, 6]
print("### next() ###")
for _ in 0 ..< 5 {
    print(rng.next())
}
print("### next(upperBound:) ###")
for _ in 0 ..< 5 {
    print(rng.next(upperBound: UInt(numbers.count)))
}
print("### random(in:) ###")
for _ in 0 ..< 5 {
    print(numbers[Int.random(in: numbers.indices, using: &rng)])
}
print("### randomElement() ###")
for _ in 0 ..< 5 {
    print(numbers.randomElement(using: &rng)!)
}

The upperBound usage is consistent with the rest of Swift.