# FX30 4g connection problem **URL:** \ **Category:** Uncategorized\ **Created:** [October 4, 2021, 7:59am UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986 "2021-10-04T07:59:00Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![angus.chao](https://avatars.discourse-cdn.com/v4/letter/a/f0a364/32.png) [@angus.chao](https://forum.legato.io/u/angus.chao)\ **Post date:** [October 4, 2021, 7:59am UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/1 "2021-10-04T07:59:00Z")
I made an application that read modbus RS485(using RENFELL RS485 2W) and send to server by MQTT. Everything work fine and after running continuously about 3 or 4 weeks(sometime over a month), it disconnected and found my application was try to reconnect but it fail. And stop my application and try to use cm data connect in terminal. but didn’t work at all. ![connect fail](https://us1.discourse-cdn.com/flex019/uploads/legato1/original/2X/0/016435816fa91716fdc8bac1ec1eeef34a337fe7.png) But after restart device, everything work fine as normal. But at develop time, I had tested that took off antenna and put it back to reconnect 4g LTE and didn’t have a problem. It was work as expected. And this is fourth time happen. Any suggestion to cover that problem? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [October 4, 2021, 8:29am UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/2 "2021-10-04T08:29:36Z")
how about doing radio software reset? AT+CFUN=0 AT+CFUN=1 ---
**Author:** ![angus.chao](https://avatars.discourse-cdn.com/v4/letter/a/f0a364/32.png) [@angus.chao](https://forum.legato.io/u/angus.chao)\ **Post date:** [October 4, 2021, 12:32pm UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/3 "2021-10-04T12:32:17Z")
Thanks for your suggest. I try it next time happen. But how can I automate to reset radio software by AT command in my c program? ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [October 4, 2021, 2:40pm UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/5 "2021-10-04T14:40:48Z")
You can send AT command inside legato app > **[How to run shell script after boot](https://mangoh.discourse.group/t/how-to-run-shell-script-after-boot/9278/14)** > > you can see this document on how to send AT command in unsandboxed legato application: Sending AT command in Legato application.docx (215.2 KB) ---
**Author:** ![angus.chao](https://avatars.discourse-cdn.com/v4/letter/a/f0a364/32.png) [@angus.chao](https://forum.legato.io/u/angus.chao)\ **Post date:** [October 13, 2021, 8:37am UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/6 "2021-10-13T08:37:46Z")
I’d tried `system("echo -ne \"AT+CFUN=0\" > /dev/ttyAT ");` but doesn’t happen expected to down radio software. In terminal, i use microcom /dev/ttyAT AT+CFUN=0 the above work as expected network was down. ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex019/user_avatar/forum.legato.io/jyijyi/32/822_2.png) [@jyijyi](https://forum.legato.io/u/jyijyi)\ **Post date:** [October 13, 2021, 8:55am UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/7 "2021-10-13T08:55:54Z")
how about using this? `system("echo -ne \"AT+CFUN=0\\\\xd\\\\xa\" > /dev/ttyAT ");` ---
**Author:** ![angus.chao](https://avatars.discourse-cdn.com/v4/letter/a/f0a364/32.png) [@angus.chao](https://forum.legato.io/u/angus.chao)\ **Post date:** [October 13, 2021, 9:04am UTC](https://forum.legato.io/t/fx30-4g-connection-problem/5986/8 "2021-10-13T09:04:59Z")
yep, it’s working. Thank you very much