一、描述你遇到的问题
按照Codelabs操作，腾讯云4G模块的几个案例，前一段时间4G模块都正常，今天连不上网，换了3个4G模块都不行，WiFi和NB模块没问题。换了三张手机卡，换运营商也连不上。
请版主验证一下，除了什么问题。
四、开发板串口所有日志
[2026-03-12_20:11:49:157]--->OK
[2026-03-12_20:11:49:157]AT CMD:
[2026-03-12_20:11:49:157]AT+QIACT=1
[2026-03-12_20:11:49:242]--->OK
[2026-03-12_20:11:49:242]Init ec600s ok
[2026-03-12_20:11:49:242]AT CMD:
[2026-03-12_20:11:49:242]AT+QIDNSGIP=1,"VIOT7WPPAM.iotcloud.tencentdevices.com"
[2026-03-12_20:11:49:242]--->OK
[2026-03-12_20:11:49:425]--->+QIURC: "dnsgip",
[2026-03-12_20:11:49:425]--->,2,10
[2026-03-12_20:11:49:425]--->+QIURC: "dnsgip",
[2026-03-12_20:11:49:516]--->+QIURC: "dnsgip",
[2026-03-12_20:11:49:516]GOT IP: 173.207.245.221
[2026-03-12_20:11:49:516]AT CMD:
[2026-03-12_20:11:49:516]AT+QISTATE=1,0
[2026-03-12_20:11:49:516]--->OK
[2026-03-12_20:11:49:516]AT CMD:
[2026-03-12_20:11:49:516]AT+QIOPEN=1,0,"TCP","173.207.245.221",1883,0,1
[2026-03-12_20:11:49:516]--->OK
[2026-03-12_20:11:53:519]establish socket 0 on module fail
[2026-03-12_20:11:53:519]mqtt connect error is 0xfffffffc
[2026-03-12_20:11:53:519]mqtt subscribe error is 0xfffffff2
[2026-03-12_20:11:53:519]MPU6050 ID = 104
[2026-03-12_20:11:53:700]mqtt publish error is 0xfffffff2
[2026-03-12_20:12:18:041]--->+QIOPEN: 0,566
以上是串口报文，请帮我看一下是什么原因，谢谢