2nd IP for residential account

I am trying to get an additional IP address added to my residential account. I just purchased a SB8200 model which has the 2 ports so I can have 2 IPs and use the link aggregation.

My issue is that no one when I call in is familiar with how to make this happen and they keep trying to up sell me to Business plan or telling me to add an additional plan with a 2nd modem.

How can I go about getting a 2nd IP on my current residential account? I am working from home, we have a hardware vpn, that need to be isolated from the home network.

Please help