FAQ ID # 225
Last Update : 2013/12/10
Rating : Not Rated
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Question / Issue
Locking Verizon / Novatel USB551L into 3G or 4G Mode

Answer / Solution

Novatel's USB551L 3G/4G/LTE USB modem has difficulty with the "hand-off" between the Verizon Wireless 3G network and 4G networks.  Users are finding that their modem works fine when locked to either 3G or 4G mode in a particular location, but when the modem is set to "auto" (i.e., when the modem is set to automatically connect to the fastest network available - 4G or 3G - this is the default setting on the modem), it has trouble making the switch between networks. This can result in difficulty making or maintaining connections in areas of marginal signal strength, modem "lock-ups" when the 4G service is temporarily interrupted, or other undesirable device behavior. Verizon has acknowledged that this is a problem and is working on a fix.

To lock the USB551L to 3G or 4G mode, follow these steps:

  • Launch the VZAccessManager software that came with your USB551L modem.  If you do not have the VZAccessManager software, download a copy from
  • Insert the USB551L modem into your PC and wait for VZAccessManager to detect the modem.
  • Press the key combination Ctrl-D to display the hidden Diagnostic Mode shown in Figure 1.  Enter the password of: diagvzw

Figure 1: VZAccessManager Diagnostic Mode Password


  • The Support Menu will be displayed.  Select the Settings button (Figure 2).

Figure 2: VZAccessManager Support Menu


  • Change the Preferred Operating Mode setting as shown below. Do not change any other settings.

 Novatel USB551L locked to 3G mode

Figure 3: USB551L Locked to 3G Mode


Novatel USB551L locked to 4G mode

Figure 4: USB551L Locked to 4G Mode


Novatel USB551L in Automatic Mode

Figure 5: USB551L in Automatic 3G/4G Mode

  • After changing the Perferred Operating Mode, click OK and wait for the configuration to be saved.
  • When complete, close the Settings and Support screens to return to VZAccessManager.
  • Close VZAccessManager.
  • Remove the USB551L from your PC.
  • Re-insert the USB551L into your PC and wait for Windows to recognize it. 
  • Launch VZAccessManager and confirm that you can make a connection in the new operating mode.

You may now insert the USB551L into your router and it will operate in the selected 3G or 4G mode.  The router configuration is the same for 3G or 4G operation - no router configuration changes should be necessary in most instances.

Related Information
Verizon Wireless / Novatel USB551L 4G/LTE Modem
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Direct Link to This FAQ

USB551L 551 551L Novatel Verizon 3G 4G LTE switch lock-up hang disconnect connect
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