IP address randomly changed wlan0

Question

I had an issue related to IP change. Is it typical for a Raspberry Pi to randomly change the IP? When I ran the command ifconfig, I noticed that under wlan0 inet, my IP address changed. I was made aware of this when I noticed I couldn't connect via SSH. I'm not sure if this was a result of me touching the wlan0 settings to set power management off and also adding and removing these two lines in the /etc/network/interfaces file:

1. source-directory /etc/network/interfaces.d
2. wireless-power off

My ultimate goal before all this happened, was to get the power management setting for Wi-Fi to be permanently off. My Raspberry Pi disconnects from the Wi-Fi network every few days.

Im hoping someone can shed some light on what happened and how to successfully stop the Wi-Fi dropping connection.

Answer 1

Default config for a Pi is DHCP addressing. The router (or switch) assigning the IP to your Pi will assign one from a pool of addresses with an express lease time set for the IP address it assigned (mapped) to the mac address of your WLAN0 interface.

Think of this IP as "loaned" to you: it's not yours in perpetuity and the address can be chucked back into the pool and reassigned to another host unless you make the ip:mac address mapping persistent in the router (or switch if it's assigning the addresses via DHCP).

A picture of a DYNAMIC DHCP lease from a Mikrotik router shown below. Note the button "Make Static": Clicking this will change the dynamic mapping to be persistent and stop the router from reassigning your IP to other hosts. Another term for this is DHCP reservation. I nail-down all my Pi IPs this way to ensure they live at predictable IP address. You can also change the default lease period to a really long time. In the picture below circled in blue you can see "Expires After" is almost a year ;-). Anyhoo, hope this help you understand the variability in your IP addressing-