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Forum Discussion
LM1200 repeatedly dropping link
I recently purchased an LM1200-100NAS to serve as an LTE failover connection for my homelab and noticed a strange issue while setting up my pfSense-based router to use the LM1200 as a secondary WAN c...
cgh wrote:
Using verizon here. I am experiencing the same issues in this thread. The disconnects between LM1200 LAN port and router port are a layer 2 issue correct? Link up/down/up/down. Why does the (MAC) layer 2 connection between the LM1200 change? What does that have to do with the Verizon wireless connection? I am using a edge router 4. For comparison, if I disconnect the coax from my cable modem, my modem and router are still connected layer 2.
Seems you are using Verizon cable box connecting to LM1200 WAN port and a router connecting to LM1200 Lan port. If this is true, the issue discussed in the thread doesn't apply to your setup. The Verizon disconnection issue happens when using Verizon wireless network.
Thanks
John, Apologies. I am not using a Verizon cable box, I am using a LM1200. I was attempting to draw comparison to another type of modem and the behavior when the service provider connection gets dropped. This might help eliminated confusion if the LM1200 LAN to router L2 connection remained persistent through provider connection dropouts. No other modem that I am aware of drops L2 link when the service provider connection drops.
cgh wrote:
John, Apologies. I am not using a Verizon cable box, I am using a LM1200. I was attempting to draw comparison to another type of modem and the behavior when the service provider connection gets dropped. This might help eliminated confusion if the LM1200 LAN to router L2 connection remained persistent through provider connection dropouts. No other modem that I am aware of drops L2 link when the service provider connection drops.OK. I got your point. By default, LM1200 is set as Bridge mode. It will pass the network assigned IP to your router. That is why when the wireless network disconnects the connection, the device will try to reconnect, refresh the IP and pass it to the router client.
Please try setting the device to Router mode to see whether it will help.
Thanks
Same issue here. Verizon data-only SIM, LM1200 connected to Ubiquiti USG Pro 4 as a failover WAN connection. Bridge mode simply doesn't work with a router at all (I've also tried two regular consumer model routers and get same result). 20 years of network engineering/IT experience and have tried all the different configurations listed in the topic to no avail (IPv4 only, 1 minute keep-alive, etc.). I am going to try the double-NATed approach with Router mode, but this is awful considering this device is advertised on the box as being "Certified with Verizon Wireless". Even if it is a "Verizon issue", Netgear should be responsibile for working with them to fix it if they've certified this device as working with their network. Guess I'll go the route of returning this device if we don't get a resolution soon :( . Also, it's a bit disconcerting that I just bought this device and it doesn't seem to be listed on the list of available Model Numbers to choose when posting on this forum...
- 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.
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.
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.
