AppsFlyer Android - Error Code 40: Failed to connect to conversions.appsflyer.com/0.0.0.0:443

Question

I'm trying to integrate the AppsFlyer SDK to my Android app but I'm just getting this error when starting AppsFlyer:

Error code 40: 
Error description: Failed to connect to conversions.appsflyer.com/0.0.0.0:443

Here's my setup code:

private fun setupAppsFlyer() {
    AppsFlyerLib.getInstance().setDebugLog(true)
    AppsFlyerLib.getInstance().init(ClubConstants.APPSFLYER.APP_ID, null, this)
    AppsFlyerLib.getInstance().start(this, ClubConstants.APPSFLYER.APP_ID, appsFlyerRequestListener())
}

private fun appsFlyerRequestListener() = object : AppsFlyerRequestListener {
    override fun onSuccess() {
        Log.d("aaaa", "AppsFlyer launch sent successfully")
    }

    override fun onError(errorCode: Int, errorDesc: String) {
        Log.d(
            "aaaa", "AppsFlyer launch failed to be sent\n" +
                    "Error code: " + errorCode + "\n"
                    + "Error description: " + errorDesc
        )
    }
}

I have the project in my AppsFlyer account and I'm using the correct dev ID. I've been following this guide https://dev.appsflyer.com/hc/docs/integrate-android-sdk