Issues with MB8600 - Speeds & Second IP

I purchased and activated a MB8600 for my gigabit service.  I have never gotten anywhere near the advertised speeds of my service.  Right now it's 319.8Mbps/4.4Mbps.  I realize that there are a lot of people working from home at the moment, but it's been about that same speed for months now.  I occassionally will get 500Mbps down.  I noticed on my xfinity account that the modem isn't even listed under devices, it's the old xfinity modem.  Is that part of my problem?

I also want to find out if a second IP is available (don't see on rate card and I know it's being phased out, but I'm hopeful) so I can keep my work stuff separated.

How do I get this stuff fixed?