You may have degraded the signal to much if you look at the splitter you will see something that has something like 6db (or ohm its been a while I don't remember). That is the amount of loss your line has, the lower the number the better. You can try to find a splitter with a lower number. Say your line comes in at a 6 loss (outside splitter), then its split inside at another 6 loss, and you split it again inside with another 6 loss, that at a rate of 18. That is a high signal loss, and for anything that is HD, it just maybe to much. This is all speculation. This is how it was when I ran cable modems a good 7 years ago, but I sure the same apply for fios. There are line amps you can get
Check out this post here. It is info on boosting your signal.