I searched for my problem, and although there are similar questions none guided me in the correct direction. Sorry if it looks like a duplicate question.

I have a LAN behind my ISP modem, routed by a TP-Link TL-WR941ND; DHCP server is up but I have some addresses reserved. I list these here:

* Raspberry Pi (ethernet) -> 192.168.0.100
* Macbook Pro (wifi) -> 192.168.0.101
* Xiaomi phone (wifi) -> 192.168.0.102
* 2nd laptop (wifi) -> 192.168.0.111
* Motorola phone (wifi) -> 192.168.0.112 
(as you can see, I jumped to .111 in case I want to add more devices of my own, .111 and .112 are devices from other members of the family).

Now the problem, I see in the DHCP client list that the Raspberry is correctly listed as "Permanent" while the Xiaomi phone has a lease countdown with address 192.168.0.103 (should be .102). I could reserve .103 for the phone and call it a day, but I don't want to have this mess in the DHCP list and also want to avoid future conflicts in the network. I give all the info I could collect here: 

I launched arp-scan from the Macbook:

```
$sudo arp-scan -I en0 -l

Interface: en0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.9 with 256 hosts
192.168.0.1     [TP-Link MAC]       TP-LINK TECHNOLOGIES CO.,LTD.
192.168.0.100   [Pi MAC]            Raspberry Pi Foundation ####<<<<----?????
192.168.0.102   [Pi MAC]            Raspberry Pi Foundation ####<<<<----?????
192.168.0.104   [guest phone MAC]   (Unknown)
192.168.0.103   [Xiaomi phone MAC]   Airgo Networks, Inc.

621 packets received by filter, 0 packets dropped by kernel
Ending arp-scan 1.9: 256 hosts scanned in 1.862 seconds (137.49 hosts/sec). 5 responded

```

On the Pi, I run ip address:

```
$ip a show eth0

 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
 link/ether b8:27:eb:0a:ec:42 brd ff:ff:ff:ff:ff:ff
 inet 192.168.0.100/24 brd 192.168.0.255 scope global eth0        ####<<<<----????
valid_lft forever preferred_lft forever
 inet 192.168.0.102/24 brd 192.168.0.255 scope global secondary eth0  ####<<<<----????
valid_lft forever preferred_lft forever
 inet6 fe80::ba27:ebff:fe0a:ec42/64 scope link
valid_lft forever preferred_lft forever

```

And on the Pi /etc/network/interfaces:

```
$cat /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)
# Please note that this file is written to be used with dhcpcd
# For static IP, consult /etc/dhcpcd.conf and 'man dhcpcd.conf'
# Include files from /etc/network/interfaces.d: source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp       ####<<<----- seems ok, right?

allow-hotplug wlan0
iface wlan0 inet manual
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

allow-hotplug wlan1
iface wlan1 inet manual
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

```

The ARP list on the router does not have any MAC bounded/linked.

I honestly don't know what's going on. I assume the Raspberry is doing weird stuff but sincerely I'm neither a Linux expert nor a sysadmin I'm a little bit lost. 

Any idea what could be going on?

Thanks in advance.