When attempting to troubleshoot cellular or PPP connections, detailed packet tracing can be extremely helpful for diagnosing possible causes.  The following steps outline how to obtain a trace on the PPP1 interface:
 

Gather traces by first going to Management– Analyser > Settings.

Ensure that the "Enable Analyser"is checked

Change the Maximum packet capture size to 1500, and the Logsize to 180.

Under Protocol layers, check Layer1 (Physical), Layer 2 (Link), and Layer 3 (Network)

Click the "Clear all Serial Interfaces"

Click the "Clear all Ethernet Interfaces"

Check PPP1 under "PPP Interfaces"

Check PPP1 under "IP Sources"

Click Apply and then save

Next, click on Trace and click "Clear Trace".

Replicate the desired behavior or wait for 5 minutes, then go to Administration - File Management >Flash Directory.

 

Save the ana.txt file which can be sent to Digi Tech. Support for analysis.