PPP Daemon intermittent failures

I am using the HL7618RD 4G modem and connect to the network via a PPP connection.

i rely on lcp-echo-failures to detect a connection has terminated

I am testing the cellular link by disconnecting the antenna.
Once the antenna is disconnected, pppd should observe lcp-echo-failures and send a notice of ‘No response to n echo-requests’,
However, sometimes we do not receive a notice (from the PPPD deamon) for the echo failures even till 15 minutes after we disconnect the antenna.

Has anyone experienced this or can recommend a solution ???

What is status of CEREG, CSQ after disconnecting antenna?
In some cases, the LTE signal is strong enough to be detected, so module is still in Connected status.
You can use AT+CEREG? to check module status, AT+CSQ to check the signal quality.
Or you can do a ping to internet from host device to see module is really disconnected or not.

Hi Dee1215,

After you set up a PPP connection, and then you remove antenna or make weak signal (+COPS:0, +CGREG:0/2), the module is not DETACHED, the local IP is still kept, i.e. the PPP connection is still kept as well. So, I don’t think you will see “lcp-echo-failures”.