LB1120 suddenly very slow with AT&T SIM

[KSP1138]

Hello. We had been using an LB1120 LTE modem for several years when it just failed. We bought a new one, and installed our existing SIM card (AT&T, from the old failed 1120) and it worked great for about one month. I have a secondary remote antenna attached for the best signal. However, we only get about three bars at most. Nevertheless, the speeds were in the 35 up and 20 down range.

However, this week, I noted a very slow connection. Now I'm lucky if I get 6 up and 8 down. I did a factory reset to no avail. As far as I know, it was all factory out of the box. We also have an AT&T hotspot modem which rocks (for us) at nearly 60 up and 30 down consistently. So today I swapped SIM cards. Same speeds, no change. The SIM card that had been in the LB1120 is now in the mobile hotspot, and its speeds are great. So it does not appear to be the SIM card or any data speed cap. I tried unplugging the antenna also. No change in speeds. 

What happened? Could something have happened to the new LB1120 to suddenly reduce its speed? Is there some setting I am missing on the device? The only hardware change we made recently was adding several more Google Mesh repeaters to the modem, but the speed drop happened several weeks after that.

Suggestions?

Thanks! CG

[michaelkenward · Accepted solution]

You've got a pretty complicate setup there. Not the sort of thing that many people here will have seen. That probably includes Netgear.

Have you talked to AT&T?

One thing to consider with a complicated setup like that is to restart the whole network in the recommended order.

Be sure to restart your network in this sequence:

• Turn off and unplug modem.
• Turn off router and computers.
• Plug in and turn on modem. Wait 2 minutes for it to connect.
• Turn on the router and wait 2 minutes for it connect.
• Turn on computers and rest of network.

[michaelkenward]

You have posted your message in the section of this community given over to Cable Modems, Routers and DSL Modems. (This is easily done, given Netgear's impenetrable community structure.)

You might get more help, and find earlier questions and answers about your hardware, in the appropriate section for your device. That's probably here:

Mobile Routers, Hotspots & Modems

I will ask the Netgear moderator to move your message.

[KSP1138]

Thank you for this! I looked high and low where to post. Inpenetrable is right! Should I, too, try and contact them? CG

[michaelkenward · Accepted solution]

You've got a pretty complicate setup there. Not the sort of thing that many people here will have seen. That probably includes Netgear.

Have you talked to AT&T?

One thing to consider with a complicated setup like that is to restart the whole network in the recommended order.

Be sure to restart your network in this sequence:

• Turn off and unplug modem.
• Turn off router and computers.
• Plug in and turn on modem. Wait 2 minutes for it to connect.
• Turn on the router and wait 2 minutes for it connect.
• Turn on computers and rest of network.

[KSP1138]

OK. Situation normal now. I took MichaelKenward's advice to a degree. Turns out it was not the modem after all. Through a process of elimination, that first had me plugging the modem directly into my laptop, I discovered my speeds returned to normal by going direct connection. I did a bit of research on the Google Wifi Mesh router system, and saw where other had had similar speed reduction issues. The two prominent "fixes" were to replace the CAT5 with a CAT6 cable (I was using the supplied cable), and a Mesh factory reset. Viola! After the Google factory reset and reinstalling the router system, my speeds are now back to where they had been. 

So, sorry for the waste of space here. I guess I am off to the Google Wifi forums to find out more information on why this happened. 

Thanks again all!

CG