@droftarts thanks for your helping!

@jay_s_uk ok, thanks for your helping!

@droftarts yes

@jay_s_uk
Hi here are the photos. It is very wired, sometimes the board can flash synchronously, but when I send M115 code, it seems that the mainboard can't read it.
I guess maybe the mainboard failed?
BTW I posted all my confiig.g code above, which has a black background .

@gloomyandy the single board did syncing when connecting at first, but suddenly it lost the connection, it is not stable. Thanks for your suggestions

@gloomyandy I tested a single board just 1 hour ago, I checked the terminating resistor and I did enable it, but it still doesn't work

@gloomyandy Hi, I checked that, sometimes one of my 1XD boards connected successfully (but it is not stable), most of the time all the 1XD boards failed to connect.

@gloomyandy Hi, when I tried connecting one at a time, I just used one RJ11 wire to connect the 6HC mainboard and one 1XD board, plugging the wire into the CAN-OUT of 6HC and CAN-IN of 1XD, nothing more.

For " How are your boards wired together ", I just used RJ11 wires to connect all the 1XD boards.
For "Something bad happened", I mean I cannot reach the DWC by now. In the past, I always used SBC mode to connect the mainboard, but now I can not visit that DWC. It failed to establish connection to the website.

@Phaedrux Hi, thanks for your replying.
I tried connecting one at a time, and it failed.
I haven't changed anything these days, and I checked the wires several times.
Something bad happened, I used to use SBC mode, so I could visit the Config.g and Console through DWC, but now I can not reach DWC (I mean the duet3.local website is not reached), so I am just able to take some pictures of the screen of the Raspberry Pi to show you the results of M122, M98 P" config.g" and my Config.g. I am sorry for the inconvenience of reading.

Hi guys, I met a very strange situation here.
All my boards (including 6HC mainboard and 1XD boards) established connection perfectly in the past, but when I powered up today, all the boards lost connection, all the 1XD boards red LED flashed quickly, while the 6HC board red LED flashed normally.
The console gived this following message
I follow the document and connect the negative terminals of the power supplies together, but it doesn't work. And I check the RJ11 wires and they are fine.
Can you guys give me some suggestions about what I am missing? Thanks gratefully for your help.