Just bought a new Moto Z4 and noticed the battery draining quickly. Checked Settings->Battery->Usage Details->Show full device usage and the two main culprits are Android OS and Mobile network standby. Called Verizon Tier 2 tech support and they couldn't figure it out. I cleared the app cache and data from Google Play Services and Play Store and that seems to temporarily fix the Android OS, as it disappeared from the list after the next full battery charge. But now it is back. Cleared the same cache and data again but this time it did not resolve Android OS being on the list. I have not been able to figure out anything to resolve the Mobile Network Standby. My son got the same phone at the same time and has not had this problem.