Are you using splitters that are rated to support MoCA? If you use the ordinary 'crappy' splitter supplied by the cable company it may be attenuating the MoCA signal which rides above 1GHz. Any splitter in your setup (attic, etc.) that isn't rated for above 1GHz effectively acts like a low-pass filter and attenuates the MoCA signal. MoCA 1.0 uses RF signals in an operating range of 850 to 1500 MHz so in general splitters should support frequencies up to 1500 MHz. I've seen some MoCA splitters on Amazon that go up to 1200 MHz and my experience is these generally work. The new MoCA 2.0 standard uses RF signals from 500 to 1650 MHz.