for you Because
can't drill new connections in to the building.
Their are adapters that can reuse
existing coax cables
to connect a cat 5 link.
one possible option
ScreenBeam Bonded MoCA 2.0 Network Adapter for High Speed Internet, Ethernet Over Coax - Single Add-On Adapter for Existing MoCA Network (Model: ECB6200S02)
item example listed
Most likely you will need the starter kit.