I'm not on 192.168.2.*

Hello, 

Can you check if the drivers are installed there are detailed steps on how to do this here 

Everything is installed.

iio_info -s  
Available contexts:
       0: (mt7921_phy0,hidpp_battery_0,acpitz,hidpp_battery_1,coretemp,nvme on Default string) [local:]
       1: 0456:b673 (Analog Devices Inc. PlutoSDR (ADALM-PLUTO)), serial=10447318ac0f0011060036002b8c172932 [usb:3.9.5]

Seems like it only sees the usb. 
Considering your router ip is 192.168.178.1 can you try these settings 

[NETWORK]
hostname = pluto
ipaddr = 192.168.178.2
ipaddr_host = 192.168.178.1
netmask = 255.255.255.0

[WLAN]
ssid_wlan = 
pwd_wlan = 
ipaddr_wlan = 

[USB_ETHERNET]
ipaddr_eth = 
netmask_eth = 255.255.255.0

[SYSTEM]
xo_correction =
udc_handle_suspend = 0
# USB Communication Device Class Compatibility Mode [rndis|ncm|ecm]
usb_ethernet_mode = ncm

[ACTIONS]
diagnostic_report = 0
dfu = 0
reset = 0
calibrate = 0

if this does not work can you try to connect using usb connection just to make sure you are able to access Pluto ?

Seems that there is the same result:

iio_info -s                                                                                                                      
Available contexts:
       0: (mt7921_phy0,hidpp_battery_0,acpitz,hidpp_battery_1,coretemp,nvme on Default string) [local:]
       1: 0456:b673 (Analog Devices Inc. PlutoSDR (ADALM-PLUTO)), serial=10447318ac0f0011060036002b8c172932 [usb:3.9.5]

But there are three new files: 

1. ipaddr-usb0, which is empty
2. status, content: "here 1:"
3. SUCCESS_ENV_UPDATE, which is empty also

These files disapear after a reboot.

can you run iio_info -u ip:192.168.178.2 
To check if we are able to see the context like this ? 

iio_info -u ip:192.168.178.2                                                                                                     
Unable to create IIO context ip:192.168.178.2: Connection refused (111)

can you try to make a firmware update following the instructions here and then try again to configure your custom ip config ? 

On 192.168.178.2 there was a repeater. The repeater is now offline and I removes it's settings in my router. Now:

iio_info -u ip:192.168.178.2                                                                                          1 ✘  3s   
Unable to create IIO context ip:192.168.178.2: No route to host (113)

For now try to update the firmware.
After the update try to run iio_info -u ip:192.168.2.1 with no other changes made. 

If this does not work use the config file bellow. 
After you update and save the file eject the device and do a power cycle this should allow you to see the ip 

[NETWORK]
hostname = pluto
ipaddr = 172.169.2.3
ipaddr_host = 172.169.2.10
netmask = 255.255.255.0

[WLAN]
ssid_wlan =
pwd_wlan =
ipaddr_wlan =

[USB_ETHERNET]
ipaddr_eth =
netmask_eth = 255.255.255.0

[SYSTEM]
xo_correction =
udc_handle_suspend = 0

[ACTIONS]
diagnostic_report = 0
dfu = 0
reset = 0
calibrate = 0