@CosimoZ 

Hi

If you are exploring the option of using your phone's hotspot as the signal source for the MR400 instead of the SIM card, it's worth noting that this particular configuration may not be supported.
MR400 only supports 4G router mode and wireless router mode.

1. 3G/4G Router Mode: The outer requires a SIM card to access the internet.
2. Wireless Router mode: The router connects to the internet via Ethernet Cable and the WAN port.