BBB can't connect over eth0

I have two beaglebone blacks. One is working fine, the other isn’t; as far as I can tell, they are nigh on identical (both Rev C–not sure what else to look at; I did get the nonfunctional one more recently and possibly from a different vendor).

I’ve tried both BBB’s booted off of the same microSD card and even then I have issues with one and not the other.

When I boot and configure the eth0 interface on one BBB, I can not ping or ssh or perform any sort of actual interactions with anything else on the network.

For instance, when I connect to a router which is running a DHCP server, I get the following from “ifconfig eth0” on the functioning BBB:

eth0 Link encap:Ethernet HWaddr 04:a3:16:ac:00:c4
inet addr:192.168.0.23 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::6a3:16ff:feac:c4/64 Scope:Link
UP BROADCAST RUNNING MULTICAST DYNAMIC MTU:1500 Metric:1
RX packets:400 errors:0 dropped:0 overruns:0 frame:0
TX packets:272 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:92719 (90.5 KiB) TX bytes:88918 (86.8 KiB)
Interrupt:175

but on the nonfunctional BBB (using the same SD card to boot) I get:

eth0 Link encap:Ethernet HWaddr 04:a3:16:b2:89:b1
inet addr:169.254.91.61 Bcast:169.254.255.255 Mask:255.255.0.0
inet6 addr: fe80::6a3:16ff:feb2:89b1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST DYNAMIC MTU:1500 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:104 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1622 (1.5 KiB) TX bytes:25334 (24.7 KiB)
Interrupt:175

The DHCP server on the router does see and give out a lease to the functioning one but does not seem to notice the non-functioning one.
If I ssh over USB into into the nonfunctioning one, running “dhclient eth0” does not appear to help anything.
If I configure a static ip address on the nonfunctioning one:
$ sudo ifconfig eth0 192.168.0.23
$ ifconfig eth0

eth0 Link encap:Ethernet HWaddr 04:a3:16:b2:89:b1
inet addr:192.168.0.23 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::6a3:16ff:feb2:89b1/64 Scope:Link
UP BROADCAST RUNNING MULTICAST DYNAMIC MTU:1500 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:121 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1622 (1.5 KiB) TX bytes:32811 (32.0 KiB)
Interrupt:175

$ ping 192.168.0.50 # Attempt to ping the router

PING 192.168.0.50 (192.168.0.50) 56(84) bytes of data.
From 192.168.0.23 icmp_seq=1 Destination Host Unreachable
From 192.168.0.23 icmp_seq=2 Destination Host Unreachable
From 192.168.0.23 icmp_seq=3 Destination Host Unreachable
From 192.168.0.23 icmp_seq=4 Destination Host Unreachable
From 192.168.0.23 icmp_seq=5 Destination Host Unreachable
From 192.168.0.23 icmp_seq=6 Destination Host Unreachable
^C
— 192.168.0.50 ping statistics —
7 packets transmitted, 0 received, +6 errors, 100% packet loss, time 6031ms

I get the same error attempting to ping the BBB from my computer, and the same issues if I attempt to connect the BBB directly to my computer’s ethernet port.

Performing exactly the same procedures, I have no issues with my other BBB. I’ve also attempted these running on the internal memory rather than the microSD card, and the issues persist.

For what it’s worth, the lights on ethernet port for the BBB are blinking.

I’m having trouble imagining what issue I could be having without it simply being a hardware issue or some subtle difference between , and I don’t really know what the hardware issue could be.

the ‘nonfunctioning’ BB does seem to be sending and receiving some packets. When you test them, do you use the same physical network connection or a different one? If different, perhaps there’s something wrong with the cable or switch port you’re using?