Mikrotik: D-Link DWM-222

Overview

DWM-222 is 4G/LTE USB modem by D-Link. This article contain configuration details and test results. USB modem was tested connected to Mikrotik RB951G-2HnD with RouterOS version v6.40.1 (stable).

Modem capabilities

• Broadband Wireless Support:
  • LTE/DC-HSPA+/HSPA/WCDMA
  • GSM/GPRS/EDGE

• Radio Frequency Bands:
  • LTE @ 2600/1800/800 MHz
  • UMTS @ 2100/900 MHh
  • Quadband GSM/GPRS/EDGE

• Data Rate:
  • LTE: 3GPP Rel-9 FDD-LTE Cat.4
    • Downlink: Up to 150 Mbps
    • Uplink: Up to 50 Mbps
  • DC-HSPA+
    • Downlink: Up to 42 Mbps
    • Uplink: Up to 5.76 Mbps

Visual indication (Status LED)

• Red (blinking): No SIM Card / No Service (or searching for service) / General Error condition
• Purple (blinking): Connected to 2G (GPRS/EDGE) network
• Blue (blinking): Connected to 3G (UTMS/HSPA/HSPA+)network
• Green (blinking): Connected to 4G (LTE) network

Note: Apparently keep alive of modem is indicated by blinking of status LED. When this status LED turn solid then it was most of the time host disconnect or firmware error/crash. Color remain as "last used" and did not switch to red. You can get modem out of this state for example by power cycling power -> /system routerboard usb power-reset duration=10s

Configuration

General configuration

This configuration is optional but I recommend to set port name. This will make configuration easier to read.

• Switch to port menu and list connected devices. Identify device by id or just by comparing output before and after connecting USB modem:

> /port print

• Set name on identified port (replace "0" with actual port number):

> /port set 0 name=Orange

• List configured ppp client interfaces:

> /interface ppp-client print

• Remove auto-configured interface (adjust name / number if necessary):

/interface ppp-client remove ppp-out1

• Add new ppp client interface:

/interface ppp-client add dial-on-demand=no disabled=no apn=internet data-channel=1 info-channel=2 name=ppp-wan port=Orange

Note1: You may add use-peer-dns=no and modem-init="<AT command>" depending on configuration.

Note2: APN depend on internet provided (cell operator).

Note3: This modem is enabled by default. Option modem-init="AT+CFUN=1" is not necessary.

Native LTE

Modem is not detected as native LTE modem in RouterOS. I am not sure if this is limitation of modem itself or missing support in Mikrotik RouterOS image. Serial "PPP" interface is working fine.

How to force access technology

Automatic selection is working fine when modem "see" strong network signal. Unfortunately this is not case when modem is installed in area with poor reception. Modem tend to jump around all access technologies under this connection. Transition between 2G and 3G is smooth but this is not case for 4G in our area (Slovakia). Each transfer to and from 4G network will cause modem to hung up and line connection needs to be re-established. It is really annoying if it is happening too often. Clear indication of this is rapid color change of status LED and often network disconnect caused by "modem hung-up".

You can force modem to use certain access technology by using AT+BMMODPREF.

• Reference table:

AT+BMMODPREF=0 -> auto
AT+BMMODPREF=2 -> Only GPRS/EDGE
AT+BMMODPREF=1 -> Only UTMS/HSPA
AT+BMMODPREF=7 -> Only LTE

Automatic selection

In this mode modem "try" to find best network connection and stick with it. Current access technology is indicated by LED and details in "info" command (see bellow).

• configuration:

/interface ppp-client set ppp-wan modem-init="AT+BMMODPREF=0"

Only GPRS/EDGE

• Configuration:

/interface ppp-client set ppp-wan modem-init="AT+BMMODPREF=2"

• Status LED: Purple

• Info indication: GSM compact

Only UTMS/HSPA

• Configuration:

/interface ppp-client set ppp-wan modem-init="AT+BMMODPREF=1"

• Status LED: Blue

• Info indication: 3G