LM1200 repeatedly dropping link

[JohnPeng]

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@solah wrote:

@JohnPeng Can you clarify that you work for / represent Netgear? What is taking so long to sort this out? Is there a solution on the horizon or should we just return our products?

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I am the PM of the project. Based the logs we collected so far and other customers' feedback, the issue points to Verizon network issue. We have a case open with them to check the network logs, but the progress is slow.

If you have to use Verizon network and the current issue really prevents you from using the device, I am OK you return it for now. We will let you know when the issue is resolved.

Thanks

[labellama]

@JinTu 

In regards to what the hAP ac2 is setting the TTL to, I don't know what I was thinking in my previous reply.

Before adding 1 to the TTL the TTL is 63, after of course it is 64.

Setting the TTL to 64 on egress to the LM1200 also mitigates the issue when using Verizon LTE.

[JinTu]

I did a quick test on this yesterday by setting net.inet.ip.stealth=1 and net.inet6.ip6.stealth=1 which forces pfSense to not decrement the TTL/Hop limit by one for traffic that transits the firewall, and observed that during the test the TTL/hop limit for all outbound traffic was never less than 64.However, this doesn't seem to have improved the connection reliability or prevented the link from dropping on failover. At least in my case, I observed the same behavior as before in that as soon as pfSense failed over to using the LM1200 for anything other than ICMP, the link dropped after a few seconds.

[STI_MECE]

I had to reply to this only because you can throw me in mix for having repeated dropped connections every 30 seconds. I can only get a consistent connection whenever I plug the LM1200 straight into my laptop, or at night ill carry it over to my smart tv and plug it in there so i watch Netflix.

How is this going on for over 6 months and still not resolved? I blame Netgear just as much as Verizon on this.

I can not setup any of my unifi devices or anything. I am literally just tied to the freaking modem with a flipping ethernet cord with nothing connected to it.

For some reason, whenever I try and have multiple devices everything just fails. I can see the flipping cell tower from my window, i got great signal.

Every time i loseconnection it picks up a new IP address. I just don't get it. Its even worse seeing how long this thread goes on for. No urgency.

[kristufer]

Also on the verizon network here. Can anyone confirm any previous version of firmware this rebooting issue was not present on with verizon? I would be happy to try a downgrade at this point until a fix is finally distributed.

Chris

[Fiddlin]

I don't remember this coming up in this thread before since I believe we've all been trying to get the LM1200 to work in bridge mode between our routers and verizon.  While testing some other things, I discovered that the exact same behavior happens when I run the LM1200 in router mode and remove my router.

Testing went as follows:

The LM1200 is in router mode on a 5-port switch

4 computers are also on the switch

All computers can ping the LM1200 successfully

When LM1200 connects to verizon, one computer can access internet web pages, but the very moment a second computer tries to access an internet page, the cell connection drops.

This surely has to be something verizon is doing to prevent multiple devices from using their service - maybe something like trying to prevent people from using their phone as a hotspot without paying for hotspot service.  It looks like we're only getting by in router mode behind a router because the router is the only device verizon can detect using the connection.

[stuyboy]

Agreed to all points above, and excellent sleuthing (we're all saying the same thing), but would like to see @JohnPeng follow up on the TTL idea that @labellama raised.  

I know that in the mobile hotspot world, many people get around hotspot data limits by playing with TTL settings (making it appear as a tablet or phone for example).  It makes sense that maybe Verizon is treating our LM1200's as USB Modems, and not hotspots to your point.

@labellama your last post seemed to indicate that setting TTL out of the router to 64 seems to work?  Most mobile phones use 65.  Is there a specific # (vs +1 on egress) that may work?  Then each of us at least know a workaround: get into your routers and reset TTL to 65, for example.

A little disappointed that Netgear is not more proactive in testing this TTL direction: and then being more creative in working around this -- such as providing an advanced setting TTL override in the LM1200.

My guess is that our routers present a different TTL for each client device (ie 128 on windows), which trips the failsafe at Verizon.  If the TTL were more stationary out of the LM1200, perhaps it would appear as any other computer/client directly connected to the modem.

[labellama]

@stuyboy setting the TTL to 65 appears to cause the link to the LM1200 exhibit the undesirable behavior, setting the TTL to 64 does not.

[sfenwick76]

I just purchased the LM1200 as a backup WAN link for my TL-R600VPN router. I have Verizon and have experience the same issues as everyone else -- the link is only up for about 5 seconds, then the link drops and this cycle repeats itself. I should have went to this support page instead of wasting several hours of my time trying to figure this out! Very frustrating. My LM1200 works fine if I connect it to a PC ethernet jack, but it exhibits this behavior if I connect it to one of the WAN ports on my router. I have tried both Bridge and Router mode, with the same results. Has anybody found a solution to this? Does anyone know if I ditch this LM1200 for another verizon hotspot like the Verizon 5G M1000 (it has an ethernet jack) will I just have the same problems?

Thanks!

[bbatty66]

I finally had to give up on this one. I have to stay with Verizon (their cell tower to the east of my location is the only reliable signal source) so after trying several other options I wound up shifting to a verizon business account with a static IP provisioned and a demo unit of an Inseego Skyus 160. Once it arrived it took me under an hour to get everything configured and running, and most of my various problems (stability, UDP packets reaching my IoT devices via my local WAP fed by the LTE gateway) went away.

I understand that with no resolution between Verizon and Netgear there is very little that might be possible to fix this. Ultimately it doesn't matter who is in the wrong here though if the LM1200 can't be made to work with a Verizon consumer LTE signal and a working solution is needed.

[JinTu]

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@bbatty66 wrote:

I understand that with no resolution between Verizon and Netgear there is very little that might be possible to fix this. Ultimately it doesn't matter who is in the wrong here though if the LM1200 can't be made to work with a Verizon consumer LTE signal and a working solution is needed.

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Given that this issue was originally reported in August of 2021 and Netgear has yet to take any meaningful steps to resolve it, all references to Verizon support should be removed from the product. As-is Netgear could be subject to litigation for false advertising under Section 43 of the Lanham Act...

[seriousolive34]

Posting on this thread to say that I too have a client using the LM1200 (Firmware EC25AFFDR07A09M4G) and experiencing connectivity issues as described on this thread on the Verizon network. @JohnPeng  the last we heard from you on this thread was on March 19, 2022 -- any updates since then?

Thanks!

[cgh]

John, A overdue follow up here. I believe the LM1200 is working as intended. It appears Verizon uses the TTL for purposes other than the intended. As I was using Edge-router, there were some unsupported workarounds that I was not willing to use. I procured a Microtix HEX router and implemented mangle to change the TTL. Microtik has the mangle built in to the UI. I also disabled IPV6. This is using the LM1200 in bridged mode. As far as I know the LM1200 isn't advertised as being able to do mangle in router mode, so I would not expect it to do that. The modem works as I would expect any modem to.

[NathanR2D2]

@JohnPeng Any updates? My Orbi RBR50 keeps dropping internet connection after a few hours with the WAN port connected to my cable modem and Verizon for LTE. Any ETA on a new firmware release address? Failover also does not work properly.

[JohnPeng]

Thanks for the update on this. This is what we suspected as well. In our internal testing, it is not only Netgear LM1200 has the same data link drop issue on Verizon network. We can saw the same issue with the brand devices. Looks like this is not something that can be resolved on device side. 

Thanks again for keep investigating on the issue for us.

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@cgh wrote:
John, A overdue follow up here. I believe the LM1200 is working as intended. It appears Verizon uses the TTL for purposes other than the intended. As I was using Edge-router, there were some unsupported workarounds that I was not willing to use. I procured a Microtix HEX router and implemented mangle to change the TTL. Microtik has the mangle built in to the UI. I also disabled IPV6. This is using the LM1200 in bridged mode. As far as I know the LM1200 isn't advertised as being able to do mangle in router mode, so I would not expect it to do that. The modem works as I would expect any modem to.

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[JohnPeng]

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@NathanR2D2 wrote:
@JohnPeng Any updates? My Orbi RBR50 keeps dropping internet connection after a few hours with the WAN port connected to my cable modem and Verizon for LTE. Any ETA on a new firmware release address? Failover also does not work properly.

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As I just replied to another customer, this is not device issue. It is related to Verizon network. If you connect a computer to the ethernet port using the same Verizon SIM card, you will not see the issue. The issue only happens when your connect a router to ethernet port and the connection is released by the network, not by the device.

Thanks

[NathanR2D2]

@Jonhpeng
I placed the LM1200 in router mode and will monitor to see if it still drops the WAN IP after a few hours. The primary connection is my cable modem with LTE as failover.

[stuyboy]

Might have to finally throw in the towel on this one.  Can't seem to replicate the success on TTL mangle that others have been able to achieve:

Verizon LTE SIM verified working

EdgeRouter X v2.0.9-hotfix.2

Disabled hardware offloading for hwnat and ipsec

iptables -t mangle -I POSTROUTING -o wwan0 -j TTL --ttl-set 64

iptables -t mangle -I PREROUTING -i wwan0 -j TTL --ttl-set 64

Tried values 62, 63, 64, 65, 66

None would maintain a solid Verizon connection.  Each time, the LM1200 would crash/reboot within 5 minutes.

Swap out the SIM for a Net10 data-only (ATT Network) and a solid connection would be maintained.

Unclear why Verizon is being so stubborn.

[Revron87]

So is there a way to change the TTL within the LM1200?

[NathanR2D2]

There is no fix. I spent wasted a considerable amount of time any money purchasing a Verizon plan going over all the forums and help. I ended up returning the unit and canceling my hotspot plan.

[SomebodyInGNV]

I just bought the LM1200 for use as a hotspot with Visible, which runs on Verizon. It connected successfully with a single computer using ethernet in router mode. Bridge mode won't connect at all, with or without anything connected to the modem. While not ideal, I'd be satisfied with router mode which, I understand, adds yet another NAT layer.

I read the first page of this topic, then jumped to the last. Without reading all intervening pages, is it possible to use this modem with a GL-iNet GL-AR750S-Ext (Slate) travel router using the TTL mangle workaround? I do that successfully tethering the travel router to a phone by USB, so I know the workaround works, in general. Does it not work with this device?

[SomebodyInGNV]

Edit to my above comment. I have now read through the entire thread. If I understand correctly, the LM1200 will remain connected in router mode with IPv6 disabled and TTL set to 64 on a router connected to it. I'll try to connect my travel router which I've used successfully tethered to a phone by USB.

[NathanR2D2]

Does your router support disabling IPv6 and setting TTL to 64 @ the CLI or menu for the WAN link? Not many consumer grade routers do unless you find one with a custom firmware. Please let us know the outcome after you have tested. I’m not sure if more than one person had success with this or not.

[SomebodyInGNV]

The LM1200 is connected to VSBLINTERNET APN in router mode. APN setup was IPV4/6 and worked, but I changed it to IPV4 based on comments read here. After reboot, it reconnected. Since it was working on IPV4/6, is there any reason to not to enable 6?

I connected the WAN port of the GL-AR750S-Ext (GL-iNet Slate travel router) to the LAN port of the LM1200 and connected my laptop to the Slate by WiFi. Speedtest on the laptop shows ping and DL results similar to what I get from a phone connected directly to Visible.

The Slate router runs on DD-WRT, uses Luci as a user interface and supports custom firewall rules. I thought I had mangled TTL to 64 but there is no custom rule to that effect. I guess I had factory reset the modem sometime in the past and not restored it. That said, it seems to work but I haven't been connected long and have no means of monitoring the connection (that I know of).

My career was in hospital software so I'm generally tech proficient but have no Linux and not much network experience beyond configuring gateways, ip addresses and DNS. I've run DD-WRT on home routers for years but had little need to use custom rules. I can follow instructions, though, if doing so can provide useful information.

Is there a way I can monitor the connection to determine if it's dropping? Since the Slate router runs DD-WRT, perhaps there are some logs I can use to track connectivity, if that's of any value. If so, I'll need instructions.

Also: Duh, having only skimmed the specs I didn't realize the LM1200 didn't have WiFi, so I can't omit the travel router, anyway. For me, the LM1200 isn't a failover device - it's my primary hotspot while camping in remote locations. I plan to connect a Waveform MIMO panel antenna to optimize reception. I know it won't work where there is none.

[SomebodyInGNV]

Addendum: This probably isn't new information to others but, after successfully connecting the Slate travel router to the LM1200 in router mode, I switched to bridged mode. The LM1200 then failed to connect to Visible. I had to connect the laptop directly to the LM1200 to access the admin panel. Switching back to router mode restored connectivity. I'm connected through it as I type this.