Concurrent connections to HiveMQ not possible

Hi everyone,

my job is to improve an already existing IoT-stack consisting of InfluxDB, HiveMQ, Telegraf and Traefik. The MQTT broker subscribes to a data source, Telegraf processes the data and saves it in the database. This works well. However, only one user is allowed to connect to HiveMQ at any time. That means if user1 is connected to HiveMQ via a tool like MQTTfx for example, and user2 wants to connect to HiveMQ via MQTTfx using different certificates, user1 gets kicked out of his session, while user2 can work fine until another user wants to connect.

We have created multiple valid certificates and I think there is no problem with HiveMQ but rather with Traefik. I will post the traefik.toml file below. It might be outdated, but if you can find the error, I would be very grateful.

# Traefik Static Configuration Reference
# Link: https://doc.traefik.io/traefik/reference/static-configuration/file/

[global]
    checkNewVersion = false
    sendAnonymousUsage = true

[api]
    insecure = true
    dashboard = true
    debug = true

[metrics]
    [metrics.influxDB2]
        address = "http://influxdb:8086"
        token = "secret-auth-token"
        org = "myorg"
        bucket = "test"
        addEntryPointsLabels = true
        addServicesLabels = true
        pushInterval = "30s"

[log]
    level = "DEBUG"

[accessLog]
    filePath = "/log/access.log"
    bufferingSize = 100
    [accessLog.filters]
        statusCodes = ["200", "300-302", "400-499"]
        retryAttempts = true
        minDuration = 10

[entryPoints]
    [entryPoints.web]
        address = ":80"
    [entryPoints.mqtt]
        address = ":8883"
    [entryPoints.websockets]
        address = ":8884"

[providers]
    [providers.docker]
        endpoint = "unix:///var/run/docker.sock"
        exposedByDefault = false
        network = "windio_stack_hivemq_cert_default"
    [providers.file]
        directory = "/etc/traefik/configurations/"
        watch = true

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