Your QNavigator software attempts to initialize the modem modules, and it attempts 10 times in 5 seconds to achieve a reply from the modem.
Why does the modem not reply the first AT command reliably each time?
This log literally indicates you know of a problem with responding to the FIRST (or more than a few) AT commands, and only after multiple retries does it work.
Why ?
How can this be fixed?
I have software that is stupid, and only attempts to open the port and send 1 (one!) “AT\r\n” and the modem RELIABLY DOES NOT REPLY that first *(or second) AT attempt.
I require this to work.
/ Start AT SYNC: Send AT every 500ms, if receive OK, SYNC success, if no OK return after sending AT 10 times, SYNC fail /
[2023-08-18 08:40:42:049_S:] AT
[2023-08-18 08:40:42:555_S:] AT
[2023-08-18 08:40:42:610_R:] AT
[2023-08-18 08:40:42:610_R:] OK << The third attempt it works
The AT command with the correct termination is AT\r
There is only one AT command termination character. There is no place for line-feed \n when submitting AT commands.
This may or may not cause an unreliable response. Also bear in mind that the modem needs time to self-initialise before it will respond to AT commands.