Describe the bug
If you use the wifi shell to auto_connect under credentials it will attempt to do so using the first L2 ethernet interface which does not consider if the interface is actualy Wi-Fi. This typically causes faults when the unhandled net management events are sent to that interface.

The code uses this snippet:

struct net_if *iface = net_if_get_first_by_type(&NET_L2_GET_NAME(ETHERNET));

when it should be

struct net_if *iface = net_if_get_first_wifi();
/* or even better  */
struct net_if *iface = net_if_get_wifi_sta();

To Reproduce
Build the wifi shell sample for the FRDM_RW612 board with theses extra configs:

CONFIG_ETH_DRIVER=y
CONFIG_NET_IF_MAX_IPV4_COUNT=3
CONFIG_NET_IF_MAX_IPV6_COUNT=3

CONFIG_NET_CONNECTION_MANAGER=y
CONFIG_WIFI_CREDENTIALS=y
CONFIG_SETTINGS=y
CONFIG_NVS=y
CONFIG_FLASH=y
CONFIG_FLASH_MAP=y
# Initialization priorities are critical here. The FlexSPI MEMC driver must
# initialize first. Then, the QSPI flash driver must initialize to program
# the LUT table for port A. Finally, the PSRAM driver can initialize and
# program the LUT table for port B
CONFIG_MEMC_MCUX_FLEXSPI_INIT_PRIORITY=0
CONFIG_FLASH_INIT_PRIORITY=50
CONFIG_MEMC_INIT_PRIORITY=60

This enables ethernet and credential manager

then add a network using wifi cred add ... the try to connect using wifi cred auto_connect

Expected behavior
Shell command should send management events to the wifi driver not the ethernet interface

Impact
Minor, shell only. Should be updated more so to serve as a good example of how to use net_mgmt, many users use the shell command as a basis for their actual code.

Environment (please complete the following information):

• OS: Ubuntu 24.04
• Toolchain Zephyr SDK
• Commit 68b2e7d

Additional context
Similar errors exist in some samples, for example the tagoio sample uses the network management with default iface, but it sends wifi specific management commands e.g. NET_REQUEST_WIFI_CONNECT which would fault on a multi interface platform like the RW612.