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Forum Discussion
pollardd
Aug 06, 2019Aspirant
4G Signal Bars drop from 5 to 2 after 30 minutes and stays that way
Hi Guys, I have a LB2120 and it is working fairly well. I'm in a regional area and have it connected to an external 4G antenna. It's permanently connected to 4G. It is not used in fail over mode. ...
pollardd
Aug 27, 2019Aspirant
Hi Blanca,
That's a good idea unfortunately I only have one antenna.
When I say it is external it's bolted to the outside of my house on a mast.
It's a good quality directional antenna worth a couple of hundred dollars so I'd be very surprised if the antenna could cause this problem. It used to work consistently on my previous modem.
I actually have a second LB2120 for use at a different site and I thought I’d try that one before I deploy it. The second device starts on 5 bars for about 30 seconds then drops back to 2.
I have done some more speed tests on both devices, while on 2 signal bars and the speed is OK. Consistantly it obtains a Ping 31ms Download ~45Mbps Upload ~ 10Mbps.
I think we will have to leave this as an "anomaly". I was hoping there was some power saving setting I could change to keep it at 5 bars but it seems I'm dreaming :)
Thanks for your assistance.
David
psynpase
Feb 15, 2020Aspirant
HI,
Only recently joined the community with a move from Huawei to a Netgear LB2120.
I also recently installed a MIMO pair of external antenna. With the Huawei I found that I had the same problem as you ( but typically after only 5 minutes). The Huawei has a slightly more sensitive rf front end than the Netgear, but in this case it did me no favours. The service provider would note that I had good signal strength and switch me to the high band, with major consequences :- my download/upload rate dropped from 80/20 Meg to 30/0.4 Meg.
The move to a Netgear LB2120 gives me 2dB less, just enough to avoid the telco shifting band! (And also provides me with Band 28 fallback)
Of course this may not be your problem, but check to see what your telcos policy is And check the modem status; you will see the band you are currently on near the bottom of the screen
- pollarddFeb 16, 2020Aspirant
Hi Psynapse,
My modem is still behaving much the same as when I originally posted.I can't see the band that it is currently connected with. I have my device in bridge mode as I have a Cisco router behind it and all the routing happens there. The LB2120 screens are actually really bland in bridge mode. I have an icon with 2/5 signal bars and it usually says 3G these days. I'd hold out no hope of ringing Telstra and asking them about this stuff and actually getting any reasonable response. Just for fun I did another speed test and Ping is 50ms Download is 6.0Mbps Upload is 1.24. This meets my needs so I just put up with it.- psynpaseFeb 18, 2020Aspirant
Hi,
Well I have been doing a little more investigation. On Github I found that somebody had written some python (called eternalegypt) .... for which many thanks. This allows you to interrogate the modem without having to go to the web page. By modifying one of these scripts and running it under cron (every 5 minutes) I have been able to log statistics. These show quite clearly that the modem starts by connecting to the B3 band and after a certain (and variable) period of time switches to the higher frequency B7 band. In the process I lose 10dB of signal strength and a great deal of upload performance (a factor of 10-20, ie from 20Mbps to less that 1). I am pretty sure that this is frequency management by the cell tower and nothing to do with the modem. However I would love to be able to lock the modem down to bands below 2GHz because I live in a rural area and radio propogation is not obvious.
My partial work around is to reboot the modem before I need to use it (simply going offline and then online does NOT resolve the problem), But in your case and IF you have the same problem then the speed with which this all happens gives you very little time to work.
For reference the B7 signal comes in at RSSI -90dB whilst the B3 signal is in the -77 to -81 range. The RSRP levels are more marked -120dB vs-105dB. If this is a firmware issue, I certainly hope that Netgear fix it!
- psynpaseFeb 18, 2020Aspirant
Just an afterthought, perhaps your aerial is too good .... what RSSI do you get when you first reboot the modem? and what does it drop to later?
The attached my measurements over 24 hours , the yellow trace is RSSI, the blue RSRP