Norton VPN intermittently blocks all internet access

I am having issues with Norton VPN blocking access to the internet-to make it more interesting, it does it intermittently. My work computer does fine with Global Connect. Is there some setting that I should change to allow consistent access? If I disable VPN, internet goes fast. If the VPN is on, it may or may not go fast, speed certainly goes down, and I may not even have internet access.