I'm running the Pi 2B headless and keep having to pull the plug because it's not connecting to the network. Sometimes it connects, sometimes it doesn't. My setup has an Ethernet cable connecting the Pi directly to a laptop (running Ubuntu 14.04). While I can't be 100% positive it's the Pi's problem, the fact that it sometimes works and that I've had trouble even when connecting it directly to a router leads me to believe the computer's DHCP server is fine.
Often the connecting works for awhile and then drops. Other times it doesn't connect at all. It can't be pinged and isn't assigned an IP address.
This got more interesting when I noticed this in
May 6 23:32:25 raspberrypi dhcpcd: eth0: carrier acquired May 6 23:32:25 raspberrypi dhcpcd: all: IPv6 kernel autoconf disabled May 6 23:32:25 raspberrypi kernel: [ 183.948122] smsc95xx 1-1.1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xC5E1 May 6 23:32:25 raspberrypi dhcpcd: eth0: IAID eb:07:6b:7c May 6 23:32:25 raspberrypi dhcpcd: eth0: soliciting a DHCP lease May 6 23:32:25 raspberrypi ifplugd(eth0): Link beat detected. May 6 23:32:25 raspberrypi kernel: [ 184.731896] smsc95xx 1-1.1:1.0 eth0: link down May 6 23:32:26 raspberrypi dhcpcd: eth0: carrier lost May 6 23:32:26 raspberrypi ifplugd(eth0): Link beat lost.
This is just an excerpt, but it shows a pattern that is repeated over and over. The entire file is available on pastebin.
Board: Pi 2B
OS: Raspbian Wheezy and Jessie (observed on both)
SD card: Verified genuine Sandisk Ultra 16GB microSDHC HSI I (class 10)
I've checked the voltage the Pi is getting and it's about 5.05V-5.10V, so that shouldn't be a problem. Also, nothing connected except the power and Ethernet.
What could be causing the problem? How can I make the connection work reliably? What other information may be helpful in diagnosing the problem?
EDIT: I should have mentioned that even when the Pi cannot connect the Ubuntu PC shows as being connected to the "Connection Sharing" Ethernet connection. Thus, the two are at least in some sort of communication.
EDIT2: It's been behaving again for the last few days (it's scared of you I guess), but I wouldn't be surprised if it happens again, given it's been so unpredictable. I'm leaving this open for now and will report back with any developments.