John, you're right. Here is compatibility list. http://www.tp-link.com/en/support/3g-comp-list/?model=TL-MR3420
I think you can try to upgrade the firmware to be latest first, reset it and reconfigure it to see what happens.

Hi,

Thanks for the reply.

My MR3420 V2 is using the latest V2 firmware 121206.

The problem I have illustrated with protocol speed is a fundamental one and I'm hopeful that when the Engineers return from New Years holiday, they can address the issues.

Best Regards

John k

Hi,

Any reply from TPLINK engineers on the serious speed/ throughput protocol issue with 4G modems?

Cheers

Here is a Beta MR3420 V2 firmware from TPLINK, which I have just received after months of nagging TPLINK for a solution to the 25Mbps limit problem.

mr3420v2_en_3_13_30_up_boot(130227)Beta.rar

I cannot test it at my current location; so any Beta testers out there that can put it through the hoops?

My latest message read:

Hi,

I have reported this problem (which is the same for all TPlink usb modem routers), a number of times, with no resolution.

Is there a Beta software version available that fixes the speed problem?

25Mbps is the maximum download speed in the TP-LINK routers, despite the same usb modem in a laptop doing 60 – 70Mbps download.

Also support for the Huawei E3276.

Thanks for firmware. I'll uploading for my polish tp-link forum. ;)

http://forum.jimasek.elektroda.eu/smf

Thanks,

Any feed-back appreciated.

Cheers

John k

PS. I have no idea what this Beta release fixes.

This was the accompanying message:

Dear Customer,

Thank you very much for your email requesting information about our product.

Please download the Beta software from the attachment.

If you need any further help, please feel free to let me know.
To get technical support more quickly, please go to http://www.tp-link.com/en/support/faq/
Best Regards
----------------------------------------------
Allan.Liu
Technical Support Engineer
TP-LINK TECHNOLOGIES CO., LTD.

Cheers

John k

Hi John

It doesn't fix the E3276 problem anyway.

It also wipes out your configs, so back up first.

Regards
Graham

Hi Graham,

Thanks.

And it does not fix the speed problem either. :(

Cheers

John K

Hi,

Good news.

We now have a BlackWidow release that fully supports the MR3420 V2 and the E3276 and ZTE MF821 and others late model modems.

Follow the links from the Whirlpool WIKI.

A couple of words of warning for users with the E3276 (other late model 3G/ 4G modems), that we have found along the way:

1. The E3276 may under some conditions (generally low signal levels), draw more power than the router can provide. This may lead to unstable performance and connection. The solution is a USB Y - Cable and an additional USB 5v supply.

2. The E3276 may under certain conditions require a USB cable with ferrite bead 'interference isolation' to ensure stable operation.

Cheers

John k

PS Please report back with your performance results and please drop into the BlackWidow support thread HERE as there are many exciting developments on the way. We know there are many downloads of this software from all over the world, so we would love to hear the feed-back.