The only thing there is a LAN connector. With this, you can also use a landline connection. This means, for example, that if you have a weak landline internet connection at home, you can use it and in parallel also 4g so that it is faster.
I have the device at home. I don't see any additional interfaces for an additional antenna on it. The device is suitable for receiving mobile radio and transmitting WLAN. You don't need any additional antennas. There is a slot for inserting the SIM card. I hope that answers your question.