Marc Shapiro via Dng <dng@???> writes:
> Yesterday, my internet connection failed. My ISP sent a tech out today.
> He replaced hardware outside, and eventually was able to connect his laptop
> directly to the ethernet where it comes into the house. It did not work
> when connected to my eero router. The tech thinks the current problem is
> with the router. I have my doubts, however, since the desktop computer
> does not get a network connection when plugged into the router or directly
> into the ethernet port.
>
> If I do:
>

>    ifdown eth0
>    ifup eth0

>
> I get the following:
>
> Listening on LPF/eth0/90:2b:34:9d:4d:6b
> Sending on LPF/eth0/90:2b:34:9d:4d:6b
> Sending on Socket/fallback
> DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 6
> .
> .
> 4 more lines like this, each with a different interval
> .
> No DHCPOFFERS received.
> No working leases in persistent database - sleeping.
>
> Did a config somehow get messed up? Is my network card malfunctioning?
> What info do you need to help diagnose this pboblem.

>From the description above, it seems that technician is right. The DHCP
server supposed to provide an address and routing information to your
computer is likely running on the router. As that doesn't work, you
won't get an address. When plugging in without the router, there's
probabyl no DHCP server at all and hence, you still don't get an
address. The reason the tech could connect directly was likely because
he either knew and address he could use or was running the necessary
software on his laptop (probably some PPPoE program, but that's just a
guess of mine).

The command

ip link show eth0

should display some information about your physical connection. If
everyting's fine, the output should be something like this:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP mode DEFAULT group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff

The 'UP' means the interface is enabled and the 'LOWER_UP' that it's
also connnecting a working ethernet port. If the port is unplugged or
otherwise not working, output should be like this:

2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN mode DEFAULT group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff

You can also check this on the NIC itself. It should have two LEDs, a
green and an orange one. The green is permanently on when carrier was
detected (link status light) the orange one blinks whenever there's
traffic on the port.

You can perhaps bypass the router and run PPPoE directly on your desktop
to connect. There's a pppoe package which provides this on top of the
ordinary pppd (Point-to-Point-Protocol Daemon). If that's supported by
your ISP, you'll likely need some login information to connect, too.