The VDV areams slow so,I'll start here.
Feel free to relocate me [Linked Image]

A single RG6 feed about 30' long into an attic. A 4-way Digital 2 gigahertz splitter. 4 taps off the splitter. One Digital box & TV won't work through the splitter, but does work with a direct inline coupling.
Would an ampilfier help?

I do this hook-up in new homes regularly with no problem, but I don't think I've ever encountered Digital CATV before.

Thanks!