I recently purchased a Vodafone 3G USB modem and TP-Link TL-MR3020 3G router. After unboxing the modem I found that it was a Huawei K3772 which is unfortunately not compatible with TP-Link routers. After much searching around I contacted TP-Link support just for a laugh. Much to my surprise they responded within a few hours! Although most of the advice was just general troubleshooting, they provided a link to toolkit for Windows for producing a so-called ‘bin file’ for loading onto the router.
Following their somewhat quirky procedure worked and I now have a bin file that can be used to get these modems working. I submitted this back to the very helpful support crew at TP-Link and they appear to have handed it on to their engineers. Just how long it will take to appear on their website though is anyone’s guess.
If you would like to make your K3772 modem work with a TP-Link router using the simplest means possible, just grab the following file, unpack it and upload it to the router under the 3G modem settings page:
In the 3G/4G page (under Network), click Modem Settings:
If there are already any files loaded, delete them and restart the router before continuing. Click Add New… to upload the bin file you downloaded above.
Once the file is uploaded, restart the router and insert the 3G modem. You can check that it is working in the Status page. The LED on the modem should also illuminate in steady light blue colour.
If you would like a copy of the USB sniffer tool and the various scripts provided, it is available from TP-Link’s FTP server at ftp://ftp.tp-link.com/Temp/3G/TP-LINK_3G_USBSniffer_Guide_105.zip. Login is tplink and the password is wr641g@. I’m not sure how long that will last so I’ve also placed a mirror on Dropbox.
For those not in the know, the reason for all the mucking about is because many of these modems present themselves as virtual CD-ROM drives when connected so that they can automatically install drivers. Once the driver is installed it sends a command to the modem to switch it into modem mode.
Usb_modeswitch is a popular Linux tool created for this exact purpose, and unpacking the MR3020 firmware image with firmware_mod_kit reveals that it uses this very tool to set up modems that are connected. The bin file above simply seems to be some obfuscated instructions for usb_modeswtich.
Update: I’ve moved the modem file to a new storage provider as Dropbox kept blocking my public links due to excessive traffic.
Another update: If you are a little more technically inclined then I’d recommend installing OpenWRT instead (if your model is supported) and setting up the 3G modem as per the 3G instructions on the OpenWRT wiki. I can confirm that this works well for the K3772. Also, if you are thinking of buying a TL-MR3020 specifically for installing OpenWRT then don’t. Get the D-Link DIR-505 instead – it is based on the same platform (Atheros AR9330) but features double the flash and memory capacity (8MB and 64MB respectively) and the power supply is built-in.