Cannot connect to LAN

[wibbles]

Hey everyone. I've been struggling to get my RPi 1B to connect to my simple LAN and I'm stumped! It's running a fresh, unmodified install of raspbian jessie lite, and I thought it would work pretty much out-of-the-box.

Things I've tried:

• checked LEDs: FDX solid green, LNK green/occasionally flashing, 100 is solid orange
• router light on the RJ45 socket for the rpi is regularly blinking orange, whereas the other LAN ports e.g. to my PC are irregularly blinking green
• checked network cable / router port with another rpi, no problem
• nmap from PC shows all the hosts on the /24 network, except the pi
• router shows no raspberrypi host, therefore no assigned IP address
• /var/log/syslog shows it's going through the motions of trying to connect to the network, though I can't figure out 100% what it's doing
• have managed to get it to work via wifi with a dongle (I added settings to wpa_supplicant), but I need it to work via wired connection

Would be most grateful for help. I'm thinking perhaps it's a hardware problem, something wrong with the network socket... I just don't know what to look for.

[B.Goode]

Would be most grateful for help. I'm thinking perhaps it's a hardware problem, something wrong with the network socket... I just don't know what to look for.

Congratulations on the troubleshooting you've done, and the description.

If you've checked the cable/socket combination with another RPi successfully, I'd be prepared to assume that your local network side of things is Ok.

In my mind that leaves 2 things to check out: the physical rj45 port on the RPi; and the OS.

Any obvious damage to the rj45 port? Lifted from the board? Any bent/displaced pins visible looking into the socket?

I have never used Jessie-lite, but for all other versions of Raspbian I have used, 'out of the box' automatic connection to a dhcp-enabled lan is the norm.

Assuming you have a console (local display) on the suspect RPi, what do the network utilities like ifconfig and ip link report? I guess the orange light will correspond with the physical link being reported as Down.

One diagnostic (not a final working solution) would be to download the NOOBS-lite (network only) Installer. It is a trivial download, and will fit on a small-capacity spare microSD card. Copy the unzipped installer to the card as documented.
Boot your suspect RPi from that NOOBS Installer card with the network connected. If it is able to bring up the network connection you will be presented with a choice of OS options with 'network' icons against them. (Not 'greyed out'.)
If you get that far, the rj45 socket on the RPi is fine and it is Jessie-lite that seems to be the issue. If you are NOT presented with any OS options, chances are the rj45 socket is faulty.

NOOBS Installer download: https://www.raspberrypi.org/downloads/noobs/

An afterthought is that the rj45 socket and the usb sockets share a common usb path on the circuit board: since you haven't mentioned not being able to use a usb keyboard or mouse this is probably NOT involved in the problem.

[ripat]

Jessie uses dhcpcd daemon to configure its interfaces.

What's the result of

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$ sudo systemctl status dhcpcd

Try also to request a new ip lease by doing:

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$ sudo dhcpcd -n
$ sudo dhcpcd -U