EM7565 Dropping Internet on T-Mobile

[MossySpringRoad]

I'm looking for help with the widely reported issue of Sierra Wireless cards losing internet connectivity, while still appearing to have a cell connection, when on T-Mobile or Sprint. I've found several reports of the same problem, down to the last detail, on this forum and also the Sierra Wireless forum, but no solution.

I have a EM7565 modem in a WG3526 router running ROOter. I'm using it on a T-Mobile prepaid data only plan. The modem loses internet access at random, at an approximate interval of every 2 to 3 hours.

When internet access goes down, the Modem -> Network Status, as well as the AT!GSTATUS command, continue to indicate the modem is connected to the cell network, including updating the signal strengths. (There are a couple a minor difference in the GSTATUS output, however, which I will post below.)

Internet access stays down indefinitely. I've found the fastest way to restore internet is to SSH into the router and run the command "ifdown wan1 && ifup wan1". This works more or less immediately. Giving the modem a reset with the command AT!RESET or power-cycling the router also restore internet, but obviously take longer.

I've stabbed around in the dark with numerous attempts at a fix or workaround: QMI and MBIM modes. Various LTE bands. Both native TMO and ex-Sprint towers. Crab leg antennas indoors or beam antennas outdoors. Multiple versions of ROOter, from the stock The Wireless Haven 2020-05-06 build up to the 2021-01-01 pre-release build.

I reset to default settings with each router firmware upgrade. Connection monitoring is off. I am using the 3 A wall wart supplied by The Wireless Haven. The APN setting is correct (fast.t-mobile.com). The same modem/router did not have this issue when I used it with AT&T.

A newer version of the modem firmware is available than what's currently installed (v. 01.11.00.00 generic). Flashing that is the next step I'm considering. It seems logical to try the TMO-specific firmware version when I do so.

[Didneywhorl]

I would go with the latest TMo firmware, update all versions really. There are new versions to Generic, now a new Tmobile, Verizon and ATT are new as well.

Which firmware version are you using now, on the modem?

[MossySpringRoad]

Current modem FW is 01.11.00.00 generic. I see latest release is 1.14.02 both generic and TMO. I've ordered the USB-M.2 adapter from The Wireless Haven so I can flash the modem.

In the meantime, I've been experimenting with disabling IPv6 on the cell-WAN interface in ROOter. Tentatively, the connection seems more stable. I've had a couple of outages since but they were possibly due to other causes. After another day or two, I should have a sense of whether nixing IPv6 is actually helping.

[Didneywhorl]

Good deal.

I'm curious of a VPN would clear it. If so you may have a proxy issue similar to what was happening to many people with ATT for a few months up to the end of last year.

[MossySpringRoad]

Disabling IPv6 on the WAN interface (both in the ROOter GUI and with the modem command AT!CUSTOM="IPV6ENABLE",0) hasn't resolved the dropouts. It may have changed the nature of the bug, as the dropouts aren't as frequent; they're happening every 6 to 12 hours now. Also, the ifdown / ifup commands no longer bring it back up. I have to do AT!RESET or powercycle.

Using a VPN full-time isn't an option for me. Awaiting delivery of USB adapter to update modem FW, but I'm not optimistic that will fix it.

I'd still appreciate any input on fixes or workarounds. Open to trying different router firmware, as a common thread in reports of this issue seems to be ROOter.

[MossySpringRoad]

Followup, five days later: I've started keeping a log of when the connection comes up and goes down -- by which I mean having actual internet connectivity. Again, the modem status shows a connection even after loss of internet.

It always goes down between 3 and 4 hours after I bring the connection up. When we aren't using internet, as overnight, I confirm the range of time it went down by looking at the system log and finding the last successful WAN DHCP renewal (attempted renewals occur hourly).

This schedule is so predictable, I've started issuing a preemptive AT!RESET command right before meetings and other important usage to make sure we get through it. That and a hard power cycle are the only things that reliably bring the connection back up and "reset the timer". Internet never comes back on its own after it goes down.

The service from this setup is completely solid when it's up, but doing a manual reset, nor implementing a scripted reset every 3 hours, is not feasible for me.

Yesterday, I flashed the modem to the latest firmware for T-Mobile, v. 1.14.02. Didn't fix it; no change in symptoms.

[Didneywhorl]

For giggles go to Network-->Firewall-->General Settings and check the box for "Drop Invalid Packets"

DropInvalidPackets.png

[WorkingOnIt]

I am having a very similar issue using Visible internet. Things seem to be OK for a day or so, but then suddenly drop for no apparent reason. The status always says it's connected. I run through the troubleshooting recs listed on this forum, but the only thing that works is to restore to defaults and set everything up again. Mine also goes out at 3am, and I wake up with it not working. I've installed/flashed the latest firmware.
I'm wondering if it is an issue with my router?

[Didneywhorl]

I'm guessing it's not the router. If it works then stops after a few hours, and only factory reset "fixes" it then something is set that is allowing a change that stops the connection and you just don't know what it is. These kinds of issues can be a pain in the butt too.
I'm guessing the reset makes the carrier believe it is a new connection and then over time it sends a request or something that causes a change.

[WorkingOnIt]

That makes sense. Thank you for thinking this through and responding! It is definitely frustrating to go through all the steps over and over again.
I am using Visible. Do you suggest that I try a different carrier all together? Or a different SIM card? Verizon's network has the best range of service in my area, which is why I went with Visible. I need unlimited, unthrottled data. What would you try?

[Didneywhorl]

Run the AT command:

Code: Select all

AT+CGDCONT?

and

Code: Select all

AT+QMBNCFG="List"

and paste the output here

[LateParrot]

I'm a little late here, but for those who don't know this is a common problem with T-mobile's network. Here's another topic on the exact same issue.
https://wirelessjoint.com/viewtopic.php?f=15&t=1407
I even get this problem when tethered to my android phone. Its a fairly consistent 3-4 hours before you hit the soft cap, then once you get deprioritized it's likely to happen at any given time. I'm on visible now, which has its own issues.