DOCSIS 3.1 problems?

A question about cable coax wiring and DOCSIS 3.1 modems. Is it possible for a building's wiring to prevent a DOCSIS 3.1 modem from connecting with an ISP, even with no problems with signal strength?

Yes. Especially if there are splitters in the cable that aren't passing the proper frequencies. I've also seen coax just twisted together or bare cable shoved into the ends of barrel splices and splitters without having any proper F-Connector on them at all.

If you have access to the cable coming into the building and an extension cord, you can take the modem to the entry point - there should at least be a grounding block connection where you can connect the modem directly to the incoming cable and see if you have problems there, eliminating all of the building wiring.