EG25 in ECM mode under Linux

I configured APN and enabled ECM mode:

AT+CGDCONT=1,"IPV4V6","resiot.m2m"
AT+QCFG="usbnet",1

After reboot I see usb0 nic under linux, but without an IP address:

pi@NanoPi-NEO-Core:~$ ifconfig usb0
usb0      Link encap:Ethernet  HWaddr ce:c9:96:67:18:6e
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:44 errors:0 dropped:0 overruns:0 frame:0
          TX packets:14 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:3184 (3.1 KB)  TX bytes:2170 (2.1 KB)

Of course, I can’t communicate.

However the modem seems connected:

AT+CGCONTRDP
+CGCONTRDP: 1,5,resiot.m2m,10.244.164.63,,194.151.228.34,194.151.228.18

OK

What’s the problem?

ATI4
Quectel
EG25
Revision: EG25GGBR07A08M2G

OK

Your host needs to request an address using DHCP.