MQTT is implemented on the backend (jolie), so again, you don't need any special handling unless you want to run the full backend on premises, which is not really the idea for most users.
About opening port 1700, perhaps in a very restrictive corporate network, like a bank, you could have problems but in that case you're anyway very unlikely to be allowed to install a device in the network. Most sane company networks will not block this, and certainly no residential network blocks this because the connection is outgoing, not incoming.