I'm using EStrong File Explorer to copy files over wifi from a Windows 7 samba share to my stock nexus 10 (5.0.2). If I keep the screen on it succeeds. If the screen goes off and it's a large file then typically it'll stop copying with a generic `copy failed` message. Retry will retry (from where it left of) and if I repeat this enough times it'll eventually finish. But this is boring, especially if copying a large number of largish files (ie video). Keep wifi on during sleep = always. I don't notice the wifi quickly reestablishing the connection whenever the screen comes back on, so it might be on all the time. Pressing the power button to turn the screen off doesn't stop every copy. Are there any other relevant settings I could check. I don't remember this problem before lollipop. The device is typically very stable; definitely a lot more so than when it had kitkat.
Our Apps
Get our official app!
The best way to access XDA on your phone
Nav Gestures
Add swipe gestures to any Android
One Handed Mode
Eases uses one hand with your phone