Dear Maintainer,

I had 2 ip addresses on my LAN (10.200.21.28 and 10.200.20.204):
$ ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group
default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP
group default qlen 1000
link/ether 1c:69:7a:09:b7:bd brd ff:ff:ff:ff:ff:ff
altname enp0s31f6
inet 10.200.21.28/23 brd 10.200.21.255 scope global eno1
valid_lft forever preferred_lft forever
inet 10.200.20.204/23 brd 10.200.21.255 scope global secondary dynamic eno1
valid_lft 691163sec preferred_lft 691163sec
inet6 fe80::1e69:7aff:fe09:b7bd/64 scope link
valid_lft forever preferred_lft forever
3: wlp0s20f3: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group
default qlen 1000
link/ether 04:ea:56:89:80:6e brd ff:ff:ff:ff:ff:ff
$

Remark: my WiFi is disabled with connman.

Fix: uninstall the Debian package "isc-dhcp-client".

Hypothesis: both connman and isc-dhcp-client were asking for a DHCP lease?

Hi,

there are two network configuration systems involved, ifupdown and connman.
To use connman only, you should probably disable eno1 in /etc/network/interfaces

Cheers,
Amy