I assume it works on the same phone in the house?
Connection might be isp locked.
Who is mobile data with?
Some providers will not allow a connection from sly.
First thing is speak to your provider to find out all this info first.
Might tell you to use a vpn, best thing to do here is find out server locations, and connect vpn to that location, mobile data with vpn tends to cause high ping and a big drop in speed, testing vpn servers in the same location will tend to keep ping down and test them out to get one with reliable speed to.