Multi-tenant Internet Access

Hello all; forwarding a question from a couple folks I know that are having issues with Comcast internet access at a seasonal resort on the East Coast.

Does anyone know how multi tenant access works? It appears that something has been put in place that prevents cable modems from syncing and actually going ‘online’. The technicians have mentioned MDTA’s and Q2Q’s which are probably in the path; but can someone provide a brief explanation of how it works?

There are somewhere on the order of 500+ tenants at the facility in question; they used to be able to get internet service over the same cabling where they were provided about 60+ standard def channels.

Any guidance appreciated.