Gateway Settings

Didn't realize this was a better place to post this than "getting started", so posting here as well.

I live in an apartment community with an Xfinity Bulk Contract. Instead of every unit getting access to a wireless gateway, it comes into the apartment in a closet to a D-link DGS-1100--08PV2 switch. How do I either get access to the Gateway settings or put it in bridge mode?