Comment 17 for bug 713385

I can also confirm this bug is still happening with the Ubuntu 18.04.2 installer. Using BOOTIF and "netcfg/choose_interface=auto" the installer defaults to using eno1 (first interface in the list). These machines all have an external network card they use the PXE boot.

I see the following messages in the installer syslog which makes it seem like it knows which interface to use but ignores it afterwards and uses a different interface:

Mar 6 03:46:42 netcfg[1195]: INFO: Starting netcfg v.1.142ubuntu7
Mar 6 03:46:42 netcfg[1195]: WARNING **: Couldn't read Wpasupplicant pid file, not trying to kill.
Mar 6 03:46:42 netcfg[1195]: DEBUG: Flusing addresses and routes on interface: eno1
Mar 6 03:46:42 netcfg[1195]: DEBUG: Flusing addresses and routes on interface: eno2
Mar 6 03:46:42 netcfg[1195]: DEBUG: Flusing addresses and routes on interface: eno3
Mar 6 03:46:42 netcfg[1195]: DEBUG: Flusing addresses and routes on interface: eno4
Mar 6 03:46:42 netcfg[1195]: DEBUG: Flusing addresses and routes on interface: enp4s0
Mar 6 03:46:42 netcfg[1195]: INFO: Found interface enp4s0 with link-layer address
Mar 6 03:46:42 netcfg[1195]: INFO: Taking down interface eno1
Mar 6 03:46:42 netcfg[1195]: INFO: Taking down interface eno2
Mar 6 03:46:42 netcfg[1195]: INFO: Taking down interface eno3
Mar 6 03:46:42 netcfg[1195]: INFO: Taking down interface eno4
Mar 6 03:46:42 netcfg[1195]: INFO: Taking down interface enp4s0
Mar 6 03:46:42 netcfg[1195]: INFO: Taking down interface lo
Mar 6 03:46:42 netcfg[1195]: INFO: Activating interface eno1
Mar 6 03:46:42 netcfg[1195]: INFO: Waiting time set to 3
Mar 6 03:46:42 netcfg[1195]: INFO: ethtool-lite: eno1: carrier down
... (repeats message for 3 seconds)
Mar 6 03:46:45 netcfg[1195]: INFO: Reached timeout for link detection on eno1
Mar 6 03:46:45 netcfg[1195]: DEBUG: Commencing network autoconfiguration on eno1

Some of the machines I've tested on it appears to have worked and some don't work at all (like the one with logs above). On the machines where it appears to work the internal interfaces are getting different names (enp6s0f0, enp6s0f1) so the external card comes first in the list (with the name enp5s0). So it just seems like it works when it's still just using the first interface in the list.

We worked around this for now by disabling the internal network card/interfaces in the BIOS so it only detects the external card.

(P.S sorry for information type updates above clicked too many times)