Help With Itunes Store Connection

Over the past couple weeks my computer has been unable to connect to the itunes store in any way. My podcasts won't update, I can't listen to itunes radio, and I can't access the store. I've had it working on one occasion when I was not at my home internet connection, but I've tried on other connections and it doesn't work in those places as well. Already tried resetting keychains and firewall and doing system updates. Any ideas on a solution to this problem?