Knowledgebase: Diagnostics
Troubleshooting LTE Connectivity Issues with DrayTek LTE Routers
Posted by Roy Panetta on 25 November 2016 11:00 AM

This document will assist you to troubleshoot LTE connectivity issues when the LTE router is unable to connect up or frequently drops the 3G/4G LTE connection. This document applies to the Vigor2860L and Vigor2925L series routers.

Information showing how to configure the LTE routers for LTE connection is available in the application note:    

Configuring the Vigor2860L and Vigor2925L for LTE Internet access 

Click here for the application note.

Instructions are also available in the video:

Configuring the Vigor2860L and Vigor2925L for LTE Internet Access

Click here to watch the video

 

1. Check the antenna installation

It is recommended to extend the antennas with extension bases to receive better signal.

This applies especially to the main antenna which is connected near the SIM card slot.

antenna

2. Check the signal strength

The signal strength (RSSI) can be found in the Online Status page as shown below.

The minimum RSSI requirement is -100dBm.  A lower number for RSSI will be better. For example:

-69 dBm (Excellent)

-65 dBm (Excellent)

-75 dBm (Good)

-89 dBm (Fair)

-101 dBm (Poor)

-102 dBm (Poor)

status

3. Check APN and SIM PIN code

Ensure the APN and SIM PIN code match the settings required by ISP.

 This can be verified by checking on your mobile devices or consulting your ISP.

4. Change Keep-Alive timer setting

 If LTE WAN drops frequently and you see 'keep alive timeout' in the syslog, it might means the SIM card not be able to ping 8.8.8.8.

 Telnet to the router and run the following CLI command to change Keep-Alive timer setting:

            % wan lte set keep_alive_on [IP]    //change destination IP of keep alive timer

            % wan lte set keep_alive_off          //disable keep alive timer

Most of the base stations disconnect idle clients to service more client connections.

Using the Keep alive timer will prevent the LTE WAN connection from being disconnected.

So we suggest changing destination IP instead of disabling the keep alive timer.

5. Collect full syslog

If above suggestions do not help with the connectivity issue, collect full syslog since the LTE initiation.

Use CLI command 'wan lte set power_recycle' to restart LTE WAN and start collecting the syslog.  Information on how to collect router syslog is available in our application note:

Capturing router syslogs for diagnostic purposes

Click here for the application note.

Once you have the syslog, sent it to our helpdesk at support@draytek.com.au for analysis.

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