Server Timeout on Freematics ONE+ (Traccar Edition)

Hi everyone. Since Traccar is so much fun, I got myself a Freematics One+ and installed the telelogger.ino sketch. I keep getting server timeouts on my end in the console and I am not quite sure where to look to fix this.
Steps taken to mitigate:

1. Google. Found a forum post where someone misconfigured the port. Made sure the UDP port is 5170.
2. Made sure 5170 UDP is open on my server.
3. Changed to demo.traccar.org, as well as demo2.traccar.org just to be sure.
4. Replaced the server name by its respective IPs (in case something is messed up in the DNS settings)
5. Made sure the APN is set correctly and #define SERVER_PROTOCOL is indeed PROTOCOL_UDP

All these changes did not lead to any different behaviour. Any idea what I am missing?

Serial log below:

11:24:41.189 -> CPU:240MHz FLASH:4MB
11:24:41.189 -> DEVICE ID:XXXXXXXX
11:24:42.187 -> TYPE:14
11:24:42.187 -> MEMS:ICM-20948
11:24:43.352 -> ACC BIAS:-0.08/-0.37/0.93
11:24:43.485 -> GNSS:OK
11:24:46.480 -> CELL:SIM7600E-H
11:24:47.511 -> IMEI:860147050016128
11:24:49.208 -> OBD:NO
11:24:49.507 -> NO SD CARD
11:24:49.540 -> [GPS] 45.XX 13.XX 0km/h SATS:6 Course:0 2021-03-24T10:24:49.500Z
11:24:49.540 -> [BUF] 12 samples | 80 bytes | 3%
11:24:49.574 -> Operator:TELEMACH Things Mobile
11:24:49.574 -> IP:10.193.XX.XX
11:24:49.607 -> RSSI:-57dBm
11:24:49.607 -> LOGIN(demo.traccar.org:5170)...
11:24:53.266 -> 
11:24:53.266 -> +CIPCLOSE: 0,0
11:24:53.266 -> 
11:24:53.266 -> OK
11:24:53.266 -> 
11:24:53.266 -> Unable to connect
(GPS and BUF information)
11:24:56.261 -> LOGIN(demo.traccar.org:5170)...
11:25:27.027 -> Server timeout

My config.h below

#ifndef CONFIG_H_INCLUDED
#define CONFIG_H_INCLUDED

/**************************************
* Circular Buffer Configuration
**************************************/
#define BUFFER_SLOTS 32 /* max number of buffer */
#define BUFFER_LENGTH 128 /* bytes per slot */
#define SERIALIZE_BUFFER_SIZE 1024 /* bytes */

/**************************************
* Configuration Definitions
**************************************/
#define NET_WIFI 1
#define NET_SIM800 2
#define NET_SIM5360 3
#define NET_SIM7600 4
#define NET_WIFI_MESH 5
#define NET_SERIAL 6

#define STORAGE_NONE 0
#define STORAGE_SPIFFS 1
#define STORAGE_SD 2

#define GNSS_NONE 0
#define GNSS_STANDALONE 1
#define GNSS_CELLULAR 2

#define PROTOCOL_UDP 1
#define PROTOCOL_HTTPS 2

#define PROTOCOL_METHOD_GET 0
#define PROTOCOL_METHOD_POST 1

/**************************************
* OBD-II configurations
**************************************/
#ifndef ENABLE_OBD
#define ENABLE_OBD 1
#endif

// maximum consecutive OBD access errors before entering standby
#define MAX_OBD_ERRORS 3

/**************************************
* Networking configurations
**************************************/
#ifndef NET_DEVICE
// change the following line to change network device
#define NET_DEVICE NET_SIM7600
// WiFi settings
#define WIFI_SSID "SSID"
#define WIFI_PASSWORD "PASSWORD"
// cellular network settings
#define CELL_APN "TM"
// Freematics Hub server settings
#define SERVER_HOST "demo2.traccar.org"
#define SERVER_PROTOCOL PROTOCOL_UDP
#endif 

// SIM card setting
#define SIM_CARD_PIN ""

// HTTPS settings
#define SERVER_METHOD PROTOCOL_METHOD_POST
#define SERVER_PATH "/hub/api"

#if !SERVER_PORT
#if SERVER_PROTOCOL == PROTOCOL_UDP
#define SERVER_PORT 5170
#elif SERVER_PROTOCOL == PROTOCOL_HTTPS
#define SERVER_PORT 443
#endif
#endif

// WiFi Mesh settings
#define WIFI_MESH_ID "123456"
#define WIFI_MESH_CHANNEL 13

// WiFi AP settings
#define WIFI_AP_SSID "TELELOGGER"
#define WIFI_AP_PASSWORD "PASSWORD"

// maximum consecutive communication errors before reconnecting
#define MAX_CONN_ERRORS_RECONNECT 3
// maximum allowed connecting time
#define MAX_CONN_TIME 10000 /* ms */
// data receiving timeout
#define DATA_RECEIVING_TIMEOUT 5000 /* ms */
// expected maximum server sync signal interval
#define SERVER_SYNC_INTERVAL 120 /* seconds, 0 to disable */
// data interval settings
#define STATIONARY_TIME_TABLE {30, 60, 180} /* seconds */
#define DATA_INTERVAL_TABLE {1000, 2000, 5000} /* ms */
#define PING_BACK_INTERVAL 900 /* seconds */

/**************************************
* Data storage configurations
**************************************/
#ifndef STORAGE
// change the following line to change storage type
#define STORAGE STORAGE_SD
#endif

/**************************************
* MEMS sensors
**************************************/
#define ENABLE_ORIENTATION 0
#ifndef ENABLE_MEMS
#define ENABLE_MEMS 1
#endif

/**************************************
* GPS
**************************************/
#ifndef GNSS
// change the following line to change GNSS setting
#define GNSS GNSS_STANDALONE
#endif
#define GPS_SERIAL_BAUDRATE 115200L
#define GPS_MOTION_TIMEOUT 180 /* seconds */

/**************************************
* Standby/wakeup
**************************************/
#define RESET_AFTER_WAKEUP 0
// motion threshold for waking up
#define MOTION_THRESHOLD 0.4f /* moving vehicle motion threshold in G */
// engine jumpstart voltage
#define JUMPSTART_VOLTAGE 14 /* V */

/**************************************
* Additional features
**************************************/
#define ENABLE_HTTPD 0
#define ENABLE_OLED 0
#define CONFIG_MODE_TIMEOUT 0

#define PIN_SENSOR1 34
#define PIN_SENSOR2 26

#define COOLING_DOWN_TEMP 65 /* celsius degrees */

#endif // CONFIG_H_INCLUDED

It looks like device doesn't receive a response it's expecting.

So this seems to be more a Freematics issue than a Traccar issue, then?

That would be my guess, but ideally you need access to the server logs to see what's going on.

Found it. Stupid mistake: I am using Traccar in Docker. The default example from the Docker documentation doesn't map port 5170.