The problem occurs when sending the HTTP request (#XHTTPREQ). After sending the initial AT message including headers
[00:00:35.041,000] <info> MODEM_NRF9160: tx:AT
[00:00:35.041,000] <info> MODEM_NRF9160: tx:#XHTTPCREQ
[00:00:35.041,000] <info> MODEM_NRF9160: tx:=
[00:00:35.041,000] <info> MODEM_NRF9160: tx:"POST","/device/api/v0/station/powerontest","User-Agent: SLM/1.2.0
Accept: application/json
Content-Type: application/octet-stream
x-boundary: ----B0uNd4Ry2018
Content-Length: 1026
Content-Disposition: form-data; name=\"log_data\"\n\
Content-Type: application/json\n\
{\n\
\"source\": \"Basestation 2.14.0\",\n\
\"stationMAC\":\"DA1111111111\",\n\
\"serialNum\":\"B00000\",\n\
\"deviceMAC\":\"DA1111111111\",\n\
\"logType\": \"Station\",\n\
\"fwVersion\": \"2.14.0\",\n\
\"sdVersion\": \"09-89-168\",\n\
\"blVersion\": 8,\n\
\"command\":\"selfTest\",\n\
\"rtc\": {\n\
\"epochTime\": 1631050498,\n\
\"batterySwitchOverFlag\": 1,\n\
\"batteryLowFlag\": 0\n\
},\n\
\"modem\": {\n\
\"fwVersion\":\"L0.0.00.00.05.08 [Apr 17 2019 19:34:02]\",\n\
\"model\":\"SARA-R410M-02B\",\n\
\"ICCID\":\"89011703278453956677\",\n\
\"CSQ\":\"+CSQ: 21,99\",\n\
\"CESQ\":\"+CESQ: 99,99,255,255,14,38\",\n\
\"IMEI\":\"352753097871972\"\n\
},\n\
\"createdAt\": \"2021-09-07T21:34:58Z\",\n\
\"epochTime\": 1631050498,\n\
\"localEpochTime\": 13143,\n\
\"tzOffset\":-14400,\n\
\"inventory\":\n\
{\n\
\"productName\" : \"Trio_Station\",\n\
\"subsystems\" : [\n\
{ \"id\" : 0, \"name\" : \"NRF_00\", \"version\" : \"2.14.0\" },\n\
{ \"id\" : 1, \"name\" : \"MODEM_00\", \"version\" : \"L0.0.00.00.05.08 [Apr 17 2019 19:34:02]\" }\n\
]\n\
}\n\
,\n\
\"last_key\":0\n\
}\n\
\n\
------B0uNd4Ry2018--"