Troubleshoot DHCP and Static IPs on FileWave Debian Appliances

What
FileWave provides Debian appliances for these components:
FileWave Server
Booster
IVS
FileWave Debian appliances use DHCP by default. The same networking principles apply to other Debian installations, but the commands and examples here focus on FileWave appliances.
Give each appliance a stable address by configuring a static IP on the appliance or creating a DHCP reservation.
Why
Every customer network has its own addressing plan. Assign a stable address during initial setup so the Server, Booster, or IVS does not unexpectedly move when a DHCP lease changes.
Information
The following articles offer details for configuring static addresses on FileWave Appliances:
FileWave Server Setup
Networking - Assign static IP Address for a FileWave Booster Appliance
IVS Control Commands
A DHCP reservation assigns the chosen IP to the appliance MAC address on the DHCP server instead of configuring the address locally.
Troubleshooting
Example customer report to the FileWave Support Team:
Report
"Despite having a DHCP reservation, the Booster was not assigned the expected IP address."
Resolution
FileWave Technical Support found two DHCP servers offering addresses on the same subnet. Only one server contained the reservation for the expected IP.
Avoid overlapping DHCP assignments
When more than one DHCP server serves a subnet:
Give each DHCP server a unique address pool. Do not let two servers offer the same addresses on one subnet.
Configure a reserved IP for an appliance MAC address on only one DHCP server for that subnet.
Place the reservation on the server that owns the desired IP range.
Overlapping address pools and relying on DHCP synchronisation is not recommended.
Use these Debian commands to inspect interfaces, leases, and neighboring devices:
Command
Description
ip a
Show network interfaces, IP addresses, and MAC addresses.
ls /sys/class/net
List network interface names.
dhclient <name of network interface>
Refresh the DHCP lease for the named interface.
arp -a
Display the network neighbor cache.
Examples:
The following 
ip a output shows two interfaces. In this example, 
ens192 carries external traffic.
# ip a
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 noprefixroute 
       valid_lft forever preferred_lft forever
2: ens192: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:0c:29:1d:1c:75 brd ff:ff:ff:ff:ff:ff
    altname enp11s0
    inet 10.85.1.9/24 brd 10.85.1.255 scope global ens192
       valid_lft forever preferred_lft forever
'lo' is the local loopback address
Use the interface output to find the MAC address needed for a DHCP reservation.
To list interface names without the address details:
# ls /sys/class/net
ens192	lo
If the appliance receives the wrong address, renew the DHCP lease for the active interface. Using 
ens192 from the example:
# dhclient ens192
Run 
dhclient as root.
arp -a can help identify address conflicts. This example shows the DHCP/DNS server and two devices in the appliance's neighbor cache.
# arp -a
Linksys38496.home (10.85.1.1) at d8:9f:80:4c:24:67 [ether] on ens192
FW1063.home (10.85.1.230) at 5c:96:cf:db:62:3b [ether] on ens192
ml1063.home (10.85.1.136) at ac:d0:74:68:23:6d [ether] on ens192
Related Content
Networking - Assign static IP Address for a FileWave Appliance