You are going to need to ensure that you know what ports SQL is listening on and ensure that the firewalls of your end pc, DSL/cable router and any ISPs involved are not blocking those ports. You will also need to know the IP address your DSL/Cable modem is pulling, as that is the IP you will have to specify from your management pc. In your DSL/Cable router you will need to ensure that port forwarding is setup so that any traffic for the SQL ports is forwarded to the pc hosting SQL.