EC800M模块连接TCP服务器经常性连接不上，偶尔能连上。是AT指令发送存在问题吗？另外AT指令经常发送后无返回或者返回ERROR，请问这是什么原因？
下面是我通过串口打印的指令收发情况：
TX:AT
RX:AT
OK
TX:ATE0
RX:ATE0
OK
TX:ATI
RX:
Quectel
EC800M
Revision: EC800MCNLER06A03M08
OK
TX:AT+CPIN?
RX:
+CPIN: READY
OK
TX:AT+CSQ
TX:AT+CSQ
TX:AT+CSQ
RX:
+CSQ: 31,99
OK
TX:AT+CGREG=0
RX:
ERROR
TX:AT+CGREG=0
RX:
ERROR
TX:AT+CGREG=0
RX:
ERROR
TX:AT+CGREG=0
TX:AT+CGREG=0
RX:
ERROR
TX:AT+CGREG=0
RX:
OK
TX:AT+CGREG?
TX:AT+CGREG?
RX:
+CGREG: 0,1
OK
TX:AT+COPS?
RX:
ERROR
TX:AT+COPS?
RX:
+COPS: 0,0,“CHN-CT”,7
OK
TX:AT+QICSGP=1,1,“CTNET”,"","",1
TX:AT+QICSGP=1,1,“CTNET”,"","",1
RX:
OK
TX:AT+QIACT=1
RX:
ERROR
TX:AT+QIACT=1
RX:
ERROR
TX:AT+QIACT=1
RX:
ERROR
TX:AT+QIACT=1
TX:AT+QIACT=1
RX:
OK
TX:AT+QIACT?
TX:AT+QIACT?
RX:
+QIACT: 1,1,1,“100.145.31.131”
OK
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR
TX:AT+QIOPEN=1,0,“TCP”,“112.17.148.146”,10086,0,2
RX:
ERROR