Solved, turns out it was a mechanical problem.

Yes it was.

Re: SD card wiped

The onboard micro sd on my duet wifi has just been destroyed for the second time. I was updating the config.g file and the sd card was wiped and is now not detected by my computer when plugged in. This first happened with the supplied card and now the replacement. Surely this must be a fault with the board.

Yes it was purchased directly from you and I was using the supplied SD card.

My duet v1.03 probably has less than a day of printing on it but yesterday the micro SD card was totally destroyed whilst printing such that the card cannot be detected. I'm wondering if there is a known cause for this and if so any precautions I can take to avoid it happening again?

I resolved the issue by installing the SD files downloaded from here; https://github.com/T3P3/Duet/tree/master/Duet2/SD Card Contents onto a new micro SD card and then adding the configuration files into the sys/ folder for anyone else facing this issue.

I've got it working thank you so much for your help. M558 S"*" got rid of the final one. I had deleted the others one at a time because of what @bricor said. After that M587 P"SSID" S"P'a's'sWORD" (with a single apostrophe in front of lower case letters on Pronterface and then M552 S1. Thanks again this has been puzzling me for a week.

I'm using pronterface at the moment which does force to uppercase. I'm using a mac. Is there something better I can try?

I think it's struggling with lowercase. I've followed the advice using apostrophes but without success. the SSID I cannot remove also contains a lower case letter. I'm unable to create a password without lowercase letters.

working on it

Hey all thanks for your responses. I managed to delete all but one of the networks. I'm currently running 1.21RC2. I re-added the correct network so have two but still can't connect.

I'm really struggling to connect to wifi. I've followed all of the getting started instructions but I'm still getting the message "Failed while trying to connect" the wifi module flashes blue when I issue an M552 S1 command but I still can't connect my router has 2.5 and 5GHz channels. I've run out of ideas. I'd really appreciate any help.