SARA R410 instability when connected with weak signal to AT&T

Has anyone else experienced the SARA R410 locking up under low signal conditions when connected to AT&T? Usually when I see it happen, it goes like this:

  1. Open a TCP socket and send some data
  2. Close the socket, modem replies “OK”
  3. The next time I am ready to send some data, the modem is totally unresponsive to the AT terminal.

I am using all of the recommended response timeouts listed in the AT Manual and all PSM (power save mode) is disabled.

The only way to recover is a hard reset using the reset pin on the modem.

I have been battling this for a while. Using a higher gain antenna seemed to help, but I am still dealing with this. Resetting the modem within the program is no problem, I am just worried about long term damage to the modem. Sometimes 10+ resets are required per day.

Sounds similar to:

Yes, very similar. I don’t see that any solution was found…

The only way I have found to keep the modem from locking up is this:

  1. Open socket, send data
  2. Close socket
  3. Put the modem into AT+CFUN=0 mode
  4. Before sending more data, put modem back to AT+CFUN=1 mode and re-attach.