It does not help that my cable company is down 80% of the time
Then, it's hard to know, if it's you, or them.
When you install firewall, basically they are all set not to prevent you from Internet connection. If you play with your firewall later on, you may screw your connection, but I don't think it's possible for firewall to interfere from the get go.
What kind of connection is it, anyway?