Beaglebone Ethernet Unresponsive Upon Idle

[Bryan Wilcutt]

I'm running a BBB with 3.14 Jessie.   I have a Verizon cell modem plugged into the USB port.  Everything works great.  I left the device idle for 1 week and then tried to ping it-- no luck, my pings were not returned.  Checking the Verizon network, the cell modem WAS connected.  The heartbeat lights on the BBB were operating normally.   A power cycle fixed the issue.  I've actually had this happen not just when using a cellular modem but plain-ol-eth0.    Long idles (how long, I don't know) tend to put the BBB to sleep.  At least on the eth0 side, if I go into a BBB terminal and do a ping to the server, the eth0 suddenly wakes up and everything is normal... until the next long idle.

Anyone have any clue what is going on?  Is this a power management sleep issue?  Can I turn all power management off on everything?

Thanks!