USB 4G modem connectivity issue (B20 & Netgear-AT&T)

We have a puzzling question pertaining to data use by a 4G modem on a Balance 20, FW 7.0.1, HW 3.

The B20 is configured with one ethernet WAN port and the USB port in use. In the USB port is an AT&T 4G modem, identified by the B20 as “Netgear Modem.” The issue is that while it is set as back-up only it is chewing up huge amounts of data. Example: During the last 24 hours it has used >215MB of data while Status | Bandwidth | Real-Time shows absolutely zero (as expected).

Here are the settings:

  • Enable: Checked
  • Connection Type: Backup priority, Group 1
  • Standby state: Disconnect [changed from remain connected, which we strongly prefer - -seems to make no difference]
  • Idle disconnect: Not checked
  • Health check method: DNS lookup
  • Health check interval: 120 [would normally use 5-10 sec but 4G is highly reliable; makes no easily discernible difference given that DNS inquiries use little data]

On a previous release of B20 firmware we recall seeing the modem status on the Dashboard to be correctly shown. However, now the modem is reported to be “Connected to AT&T.” How is it that it is connected (10.10.143.x) and using relatively large amounts of data when it has been set to be in standby status?

Early this Spring we noted that with this 4G modem set as a back-up but in “Remain connected” status it used just a few MB a day, mostly in the middle of the night. This was expected as a result of AT&T “house-keeping.”

Essentially, the modem is using large amounts of data but is doing no “work.” We’re wondering if something was changed in a recent version of the FW to change the behavior of this device, Or perhaps a code regression in the modem support package(s)?

This is strange… May I know the daily usage is almost same every day?

Please help to open ticket for us to take closer look. We might need to sniff the traffic.

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Hi TK. Thanks for your response. Yes, strange indeed! :face_with_raised_eyebrow:

I can’t be certain if the data used is the same each day as the B20 shows no usage and we have not checked with the carrier (AT&T) to see what usage has been on a daily basis.

One thing to note, however, is that even though the USB modem is set as a back-up and is disconnected, the Dashboard shows it to be on-line. Actually, the Dashboard indication never changes regardless of modem status.

Ticket #775680. Again, TU.


This is well noted. I will follow up from there.


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