Vitrtual Private Network

I am working from home and need to access my companies network remotely using a VPN. I successfully connected the first day with support from our IT department, but now I get an error message saying "The service provider in your current location is restricting access to the Internet. You need to log on with the service provider before you can establish a VPN session. You can try this by visiting any website with your browser." Internet and streaming seem to be working fine. Any one know what the problem is? Currently ATT technical support is unreachable.