Redid everything using the RRF config tool and it seems to be working now.

I just updated everything in hopes of fixing the problem

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

I added a fan and set it up using the RRF config tool and installed it using DWC. Now, if I try to simulate or print I get this message. I have updated the firmware and DWC, tried previous working config files, and no matter what I do I get this message. Help! I'm not a software guy by any means.

JavaScript Error

A JavaScript error has occurred so the web interface has closed the connection to your board. It is recommended to reload the web interface now. If this happens again, please contact the author and share this error message:

Version: 1.22.6
Message: Uncaught TypeError: Reduce of empty array with no initial value
URL: http://192.168.29.233/js/dwc.js
Line: 1413:46
Error object: {}

Ah, ok. What should I set it to? 3?

Here's a dump of config.g file

; Configuration file for Duet WiFi (firmware version 1.21)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v2 on Mon Jun 24 2019 19:38:23 GMT-0700 (Pacific Daylight Time)

; General preferences
G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves

; Network
M550 P"My Printer" ; Set machine name
M552 S1 ; Enable network
;*** Access point is configured manually via M587
M586 P0 S1 ; Enable HTTP
M586 P1 S0 ; Disable FTP
M586 P2 S0 ; Disable Telnet

; Drives
M569 P0 S0 ; Physical drive 0 goes backwards
M569 P1 S1 ; Physical drive 1 goes forwards
M569 P4 S0 ; Physical drive 4 goes backwards
M569 P3 S1 ; Physical drive 3 goes forwards
M584 X0 Y1 Z4 E3 ; Apply custom drive mapping
M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
M92 X80.00 Y80.00 Z2560.00 E407.00 ; Set steps per mm
M566 X900.00 Y900.00 Z12.00 E120.00 ; Set maximum instantaneous speed changes (mm/min)
M203 X6000.00 Y6000.00 Z180.00 E1200.00 ; Set maximum speeds (mm/min)
M201 X500.00 Y500.00 Z20.00 E250.00 ; Set accelerations (mm/s^2)
M906 X800.00 Y800.00 Z800.00 E800.00 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Axis Limits
M208 X-33 Y-12 Z0 S1 ; Set axis minima
M208 X230 Y210 Z200 S0 ; Set axis maxima

; Endstops
M574 X1 Y1 Z1 S1 ; Set active high endstops

; Z-Probe
M558 P0 H5 F120 T6000 ; Disable Z probe but set dive height, probe speed and travel speed
M557 X-18:195 Y3:195 S20 ; Define mesh grid

; Heaters
M305 P0 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 0
M143 H0 S120 ; Set temperature limit for heater 0 to 120C
M305 P1 T100000 B4138 R4700 ; Set thermistor + ADC parameters for heater 1
M143 H1 S280 ; Set temperature limit for heater 1 to 280C

; Fans
M106 P0 S0.3 I0 F500 H-1 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Tools
M563 P0 H1 ; Define tool 0
G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C

; Automatic saving after power loss is not enabled

; Custom settings are not configured

I checked the config.g file and it does show M584 X0 Y1 Z4 E3; apply custom drive mapping
The next line is the M350 and a few lines down is the M906. What else can I check?

I have a duet wifi 2 that I've been using for a few months now and the prints have been fantastic. Everything had been dialed in tight and right up until about a month ago. I'd like to remap my Z axis to the spare extruder driver. When I set the Z axis to E1 in RRF I can control the axis and everything works, except I my extruder (E0) no longer works. How do I fix this?