Sounds like you've got a bad coax.
Check your MOCA LAN stats.
»Verizon Online FiOS FAQ
»How to check MOCA stats?
Please do this three times:
1) With A-B switch in the STB position.
2) With A-B switch in the ECB200 position.
3) With the splitter connected instead of the A-B switch.--
There are 10 kinds of people in the world; those who understand binary and those who don't.