TP-Link TL-MR3420

[DTMark]

Hello,

Our area recently got upgraded for DC-HSPA. This required a new dongle, which is an E3256.

That in turn required a new router, and the only one I can find that's compatible with that dongle was the TP-Link MR3420.

Except that it wasn't. When I plugged in the dongle it would connect briefly, pull down a small amount of data, then drop the connection to the dongle and need restarting.

I was about to return it as not compatible when I thought, by chance, to try plugging the dongle into the router USB slot directly (no USB cable). Works fine.

5m cable - no light on USB dongle.
3m cable - light comes on, drops - behaves as above
10" cable - works fine

I wonder if is because the router is not supplying enough power down the USB cable.

Anyway that's been running for a couple of months, but now the router appears to be dying.

Request web page - fine. Request it again - page cannot be displayed. Again - partly loads. Again - loads fine.

Run ping -t while it's doing that - no packet loss, no timeouts, all looks good.

Modem signal strength wanders about - 1 bar, 3 bars, 5 bars, goes into H+ then 3G then G then back to H+

Whereas if I plug the dongle directly into my PC - 5 bars (as always - it's not a signal issue) and no problems at all.

Not a problem with that PC (e.g. the network card) - issue affects all connected devices.

Back on the router - almost unusable. It's close to complete failure now.

Tried forcing Open DNS servers in router - no, it's not that.

Router log shows nothing relevant that I can see.

It's simply as though some packets die when passing through the router. Randomly. Any protocol.

Theory built on a theory - I wonder if the power supply to the dongle has fried itself.

Can anyone relate to these issues with this router?

There is just one alternative, but it's really expensive - a HUAWEI B593-4G B593 but I think I may have to go for that, since the other problem with the TP-Link one is that since you cannot use a USB cable of any length, you cannot optimise the dongle location.

Anything that you can think of that's worth checking before I put it in a box and send it back to Amazon for a refund...

As an aside I pressed the issue about the USB cable/power with TP Link who said that perhaps it's a problem with the USB cable, if it works when you plug the dongle in directly it is performing as it should, and denied that this is an issue. And also told me not to put the router on the window sill, even after saying I had no choice because the router must go where the dongle goes, they cannot be apart.

Thanks,
Mark

 

[JimM]

Guaranteed a power problem.

A cheap fix is a powered USB hub at the modem end of the longer cable.

 

[sajunky]

I am surprised why you shouldn't put router on window sill, maybe they are concerned about optimum WiFi propagation.

Request web page - fine. Request it again - page cannot be displayed. Again - partly loads. Again - loads fine.

Run ping -t while it's doing that - no packet loss, no timeouts, all looks good.

Modem signal strength wanders about - 1 bar, 3 bars, 5 bars, goes into H+ then 3G then G then back to H+

It worked on short cable, but now doesn't. It shows that capacitors are drying out either on power adapter, router, or on the modem itself. It is possible that signal is lower now and modem is allowed to transmit more power.
Other behaviour (quoted) is consistent with power problems. Hunting for signal, as it cannot maintain connection with existing tower. Pings are stable, as ping traffic is not enough to trigger transition to HSPA+ mode and energy stored in capacitors is sufficient. When more traffic is requested, it requires more power and voltage drops below critical level, transmission is interrupted, lost packets. Try a hub as suggested - once again - plug modem directly to the hub, now you can use longer cable between hub and router (up to 5 meters).

 

[DTMark]

Thanks very much for your diagnosis.

I must admit that a powered USB hub didn't even occur to me. I shall get one.

My only concern is that the router might have been physically damaged, but I won't know until I try.

With regard to the positioning - my dialog with TP Link was that in order to get the best signal the modem needs to be near a particular window facing a certain way.

Because the router does not permit the use of a USB cable of any length, aside from the fact that I very nearly returned it as incompatible and the other thread about this router on here suggests others might have done same, I pointed out that having the router in that location isn't a great idea as it's in direct sunlight and could get rained on if the window is open.

But then because the router and the modem cannot be separated from each other, there is no alternative. I was angling for a fix for the power levels, but according to TP Link this is not a fault or a problem. The router works perfectly. Yet even though it can only go in one location, that location is "not recommended".

I don't think it has got wet, but this design flaw doesn't bode well. On the other hand we have 4G here now, so I may move away from this anyway, it will work in the meantime.

If it behaves the same with the powered hub, I'll get a refund and go for that expensive Hauwei one as that will work for 4G, too.

Thanks all.

 

[lotus123]

Hi Mark

These Huawei modems are fierce on power, and the router alone just can't feed their appetite. I had the same issue with my E3276 modem and 3420v2 router, until I connected it via a powered hub.

I should also mention that the stock TPLink firmware is not very good. My compatibility and performance problems were finally solved with the OpenWRT Rooter software. I suggest you give it a try.

http://forums.whirlpool.net.au/forum-replies.cfm?t=2135188&p=24
http://ofmodemsandmen.com/

This software not only got the E3276 working properly, it also meant that I could finally get LTE going on this router.

Hope this helps
Graham

 

[DTMark]

Again thank you. There's just one other oddity which I wondered about - could anyone shed any light...

Sometimes, the connection (LAN to PC) will show "No internet" (yellow icon in task bar).

At this point, the router looks perfectly normal and the dongle light is on. All looks good, just no connectivity.

Drop the LAN connection and enable the WiFi one and back it comes. IP address doesn't change. There has been no network reconnect.

Maybe half an hour later, it goes down again, so drop WiFi and re-enable LAN - solves it. This can go on all day long. Or it might go all day without doing it once.

It's not just the PC because all the other devices are connected via WiFi and they suffer these random connectivity breaks, too.

Must this problem necessarily be a fault with the router?

 

[Marius in Africa]

Hi people

Please offer me some advise on a suitable "powered hub" to use with the MR3420 V2 and E3276 modem fitted with a LTE sim card. I do have a STLab U-810 USB hub (Ethernet adaptor) but clearly this device is not what is needed.

Thank you for your help.

Regards
Marius

 

[1geoff99]

Are you sure you need a powered hub? I have exactly the same router and modem as you and I did not need a hub when I was using them together. (I am now using a different TP-Link router and I still do not need a powered hub with my E3276s-920 with Telkom LTE). Also make sure you are using the latest MR3420 v2 firmware as this may resolve issues you may be having.

EDIT: As a matter of interest, info from this link provides proof that the E3276 modem is NOT power-hungry.

 

[midnightcaller]

Has anyone tried to power the MR3420 with a 12v battery.
With all the load shedding, I'm looking for a way to keep my internet connection going.

Any ideas ?