模块 UART 口TCP 缓存模式能发送并接受第一条数据，第二次发送数据上行"不转发（USB 正常、重连正常、服务端正常、Wireshark 无报文、假 ACK），AT+QISEND=0,0 //查询发送数据长度，显示发送。
[16:26:50.724]收←◆[I] TX sent: 85 bytes, data: {“msg_type”:“heartbeat”,“device_id”:“DEV_25187_001”,“uptime_s”:146,“heartbeat_seq”:5}
[16:26:50.780]收←◆[I] AT>> AT+QISEND=0,85
[I] AT<< AT+QISEND=0,85
>
[16:26:50.854]收←◆[I] AT>> AT+QISEND=0,0
[I] AT<< AT+QISEND=0,0
+QISEND: 547,547,0
OK
[I] TX result: ACKED, len=85
[W] Heartbeat ack timeout, count=4
[I] RX diag: idle_irq=50(+4) cb=50(+4) bytes=1018 ring=0 dma_pos=506 ORE=0 FE=0 NE=0
[16:27:00.879]收←◆[I] RX diag: idle_irq=50(+0) cb=50(+0) bytes=1018 ring=0 dma_pos=506 ORE=0 FE=0 NE=0
[16:27:10.720]收←◆[I] TX sent: 85 bytes, data: {“msg_type”:“heartbeat”,“device_id”:“DEV_25187_001”,“uptime_s”:166,“heartbeat_seq”:6}
[16:27:10.780]收←◆[I] AT>> AT+QISEND=0,85
[I] AT<< AT+QISEND=0,85
>
[16:27:10.855]收←◆[I] AT>> AT+QISEND=0,0
[I] AT<< AT+QISEND=0,0
+QISEND: 632,632,0
OK
[I] TX result: ACKED, len=85