Network SSID of portable Wi-Fi hotspot is incorrect. Why?
When you perform the initial set up of Wi-Fi hotspot, SSID is the last 4 digits of your phone number.
1. SSID is shown as 'Model _last 4 digits (of your phone number)' during the initial booting.
How to setup
If you have different SSID, this is because you've performed initial boot without inserting a SIM card.
This is normal behavior and you are able to change SSID number through setting.
Settings > Tethering & networks > Wi-Fi hotspot
Set up Wi-Fi hotspot