Error code
AC4
Meaning
Your dryer's WiFi connection isn't working
Moderate
What to do
Why this happens
Possible causes include faulty soldering on the WiFi module, communication failure between the WiFi PBA and main PBA, or a failure in the main PBA's WiFi circuit. Additionally, entering line test mode after completing the dry procedure could be responsible.
How to fix it
Try reconnecting the dryer to WiFi through the SmartThings app. If it won't connect, restart your router and try again.
SourceSamsung service manual