As title
The only way is to call isp?

yes or use their support app if they have any

LOS means Loss Of Signal. Means your incoming internet connection already severed. Need call them and ask. You cant repair it yourself. Unless you have proper tools.

yes

Must call them. Usually they’ll send a tech next working day to fix the issue. If landed property, it’s often an issue with your port in the pole behind your house or the cable leading to it. If problem outside your house then you don’t need to pay.