@dc42 This is almost a year old, but I am now having this issue. I cannot upload files to my Duet WiFi from PrusaSlicer any more, but was in the past. I have changed routers and seeing that 1.21 had issues with some routers, I'm thinking it may be similar. It also fails when using the Upload button in the web interface. It doesn't fail at the same location.

How do you do a WireShark trace?

Firmware Name: RepRapFirmware for Duet 2 WiFi/Ethernet
Firmware Electronics: Duet WiFi 1.02 or later + DueX5
Firmware Version: 2.03 (2019-06-13b2)
WiFi Server Version: 1.23
Web Interface Version: 1.22.6

M122
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 2.03 running on Duet WiFi 1.02 or later + DueX5
Board ID: 08DGM-917DA-G4MS8-6J1F2-3S06R-T9THB
Used output buffers: 3 of 24 (8 max)
=== RTOS ===
Static ram: 25680
Dynamic ram: 94148 of which 416 recycled
Exception stack ram used: 320
Never used ram: 10508
Tasks: NETWORK(ready,524) HEAT(blocked,1236) DUEX(suspended,156) MAIN(running,3748) IDLE(ready,160)
Owned mutexes:
=== Platform ===
Last reset 00:07:10 ago, cause: software
Last software reset at 2020-01-14 17:21, reason: User, spinning module GCodes, available RAM 10372 bytes (slot 0)
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0441f000 BFAR 0xe000ed38 SP 0xffffffff Task 0x4e49414d
Error status: 0
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest block write time: 6.0ms, max retries 0
MCU temperature: min 34.6, current 34.8, max 35.6
Supply voltage: min 24.2, current 24.3, max 24.5, under voltage events: 0, over voltage events: 0, power good: yes
Driver 0: standstill, SG min/max not available
Driver 1: standstill, SG min/max not available
Driver 2: standstill, SG min/max not available
Driver 3: standstill, SG min/max not available
Driver 4: standstill, SG min/max not available
Driver 5: standstill, SG min/max not available
Driver 6: standstill, SG min/max not available
Driver 7: standstill, SG min/max not available
Driver 8: standstill, SG min/max not available
Driver 9: standstill, SG min/max not available
Date/time: 2020-01-14 17:28:29
Cache data hit count 1688952282
Slowest loop: 8.35ms; fastest: 0.07ms
I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
=== Move ===
Hiccups: 0, FreeDm: 169, MinFreeDm: 169, MaxWait: 0ms
Bed compensation in use: none, comp offset 0.000
=== DDARing ===
Scheduled moves: 0, completed moves: 0, StepErrors: 0, LaErrors: 0, Underruns: 0, 0
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1
Heater 1 is on, I-accum = 0.0
=== GCodes ===
Segments left: 0
Stack records: 1 allocated, 0 in use
Movement lock held by null
http is idle in state(s) 0
telnet is idle in state(s) 0
file is idle in state(s) 0
serial is idle in state(s) 0
aux is idle in state(s) 0
daemon is idle in state(s) 0
queue is idle in state(s) 0
autopause is idle in state(s) 0
Code queue is empty.
=== Network ===
Slowest loop: 81.74ms; fastest: 0.00ms
Responder states: HTTP(0) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0) Telnet(0)
HTTP sessions: 1 of 8

WiFi -
Network state is running
WiFi module is connected to access point
Failed messages: pending 0, notready 0, noresp 0
WiFi firmware version 1.23
WiFi MAC address
WiFi Vcc 3.36, reset reason Turned on by main processor
WiFi flash size 4194304, free heap 20080
WiFi IP address 192.168.1.197
WiFi signal strength -67dBm, reconnections 0, sleep mode modem
Socket states: 0 0 0 0 0 0 0 0