@educatingsavvas said in M291 S3 not blocking when called with M98:
WiFi firmware version 1.23
Not really related, but your wifi server is a bit out of date. How have you been updating the firmware? Regardless, you should be able to update just the wifi firmware by uploading the latest version.
https://github.com/Duet3D/RepRapFirmware/releases/download/3.3/DuetWiFiServer.bin