It seems the 3G connection is not so stable. Firstly you need to make sure the modem is working fine on the computer. Plug the modem to the computer and see whether the problem persists or not. If there is no problem between the computer and the modem, that should be the cooperation between the modem and the router, then try to reset the router and reconfigure it.

Hi,
When connecting the modem directly to the computer, it works fine evry time, It takes just a few seconds to get connected.
When the modem is connected to the MR3220, it is really unpredictable. Sometimes it just says "unplugged", sometimes it is identidied and connecting, and sometimes after it was identified, it suddenly changes to "unplugged" even though the modem is still physically attached to the router.
It is really frustrating.
I also don't understand why the identifiaction process should go on every time from the beginning. Since most of us are using the same modem time after time, it makes sense to "remember" the last working configuration and try it first the next time power is switched on. It looks like amature programming to me.

I think I figured out what's going on:
By looking at the logs, one can see that the router starts communicating with the modem on the same second the power is switched on. It reads "handle_card_start".
This often leads to an error later on in the log and at that point the status reads "unplugged".
However, if you first let the modem startup normally and only then begin the communication process with the router, everything goes well and it gets connected every time. This
can be done by moving the mode switch on the router from 3g to wisp or ap and then back to 3g. The modem still gets power when this is done and stays connected, and the router restarts.
This makes sure that the modem is ready to receive the router's communication.
TP Link should release a firmware that will wait a few seconds after power on before starting the communication process with the modem.

Hi,

There is growing evidence that some modems may exceed the TP-Link router USB power source, causing a variety of problems.

This only occurs in weak signal areas when the modem is at maximum transmit power.

Is your signal weak?

Try a USB Y-cable


and connect it to a 2nd source of USB power.

The use of a USB cable with a ferrite bead interference suppressor may also be beneficial.

Cheers

John k

Hi!

I'm desperately trying to get mr3220 working stable.
I have tried two different 3g/4g modems in MR3220 but none of them works stable in router. When plugged to computer both modems work very well.
I have also tried to use additional usb y-cable without any improvement.
I also measured the current consumption of modem. It shows about 100-150mA for the modem(s) when plugged to computer. Too much for the router???

Modem goes to unplugged state totally randomly. Sometimes it works less than 1 hour sometimes 10 hours. Only wlan is used for networking.
After modem status has changed to "unplugged" only way to get it back working is reboot of the router.

One common feature when unexpected unplugging has happened is these rows in log:


127 Jun 8 10:45:01 3G/4G NOTICE modemUnplugedTime >=60s
126 Jun 8 10:44:05 3G/4G INFO 3G Modem is plugged out.
125 Jun 8 10:44:04 3G/4G NOTICE dhcpcLteModemRelease 998 sysCmd = ifconfig lte0 0.0.0.0
124 Jun 8 10:44:02 DHCP INFO dhcpc_ipc_data_rcv_router 648 : current network type = 1
123 Jun 8 10:44:02 DHCP NOTICE DHCPC Entering released state
122 Jun 8 10:44:02 DHCP NOTICE DHCPC Unicasting a release of 10.13.92.172 to 10.13.92.169
121 Jun 8 10:44:01 3G/4G INFO process_msg 385 : call dhcpcLteModemRelease
120 Jun 8 10:44:01 3G/4G INFO LTE MODEM = 0, status = 0, targetVendorID = 0x0, targetProductID = 0x0
119 Jun 8 10:44:01 3G/4G INFO LTE MODEM = 0, status = 1, targetVendorID = 0x0, targetProductID = 0x0
118 Jun 8 10:44:01 3G/4G NOTICE handle_card start

Any ideas what to do??
Router is MR-3220 Ver 2.2

Firmware version is: 3.15.2 Build 130423 Rel.61823n
Hardware:MR3220 v2 00000000

Hi,

How long is your USB cable?

Are you in a week signal area?

Cheers

John k

I've tested 0.5 meter y-cable and 1.5 meter y-cable. No big difference between them.
On my location 3G signal is pretty good (around 75...98% signal strenght).
4G is not available here and thus I've made modem setting manually so that it is using always 3G.

Hi.
Maybe you can change 3G connection mode to connect manually on the router for a try. And disable Pin code on the modem.

Thanks for reply, but unfortunately changing the connection mode doesn't make big difference on stability. I have a feeling that when connection mode is set "on demand" and max. idle time 0 it works bit longer without unplugging the modem.
I'm still thinking that it is something with DHCP. There is always same things recorded in mr3220 log when the modem unplugging happens.