I am using the note 4 for about 6 months now. The poor signal is becoming in tolerable at home, it will go through the cycle of 4G 2 bar, 1 bar, 3G, 1X, no signal. We also own samsung S5 and iphone 6 and both have very stable 4G (2-3 bars) signal right next to the note4!
To be exact, when my note 4 has a signal strength of 118 dbm, the other phones have 110 dbm or better, even with the SAME cell station (based on app "network info").
I called the Verizon technical support. They were very nice and sent me a new sim card. But that did not solve the problem.
I then reset the phone, and reverted it back to kitkat 4.4, and that did not help. So it was not lollipop upgrade.
I am now back to lollipop via OTA and the signal is as weak as before.
I don't think I have a bad phone because it is superb at work where I have full xLTE signal (4-5 bars).
In conclusion, note 4 either has a weaker antenna or it needs a software fix.