@joernupbde - I tested Chessnut Air, Chessnut Go, and Millenium e-One on Lichess with the Edge browser and Beta version 4.2.1, all boards worked well.
I did have an issue getting the Lichess API key to connect using the Chrome browser. It never seems to find my username. I deleted the key twice and recreated it. The current key works fine in Edge.
Nobody has mentioned Chessconnect missing moves on DGT e-boards for a while. Has that issue disappeared or are DGT e-boards now considered impossible to get truly stable?
@Rsava: I've had several reports of problems with Lichess tokens. Unfortunately, I am unable to reproduce this here. So, if someone finds a way to recreate this problem - ideally with a newly created token - that would be really helpful.
@jewelmind: I guess there is still a chance for Chessconnect missing moves. But it is getting increasingly robust.
@joernupbde - update below
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my steps to reproduce are simple:
Create new token
Enter it into the extension under the API-Token (Lichess) tab
It states "Checking token" as above
I then get this error message
I click "OK", it pops up again, then goes away.
The token does have "board play" enabled and it works immediately in Edge.
If there are any logs I can get, I will be more than happy to grab them for you.
I just made sure the two flags are set in Chrome that are listed on the website. I have removed and added the extension several times, restarting Chrome in between.
Could it be that there is something in Chrome that needs to be set? I am running Chrome Version 127.0.6533.89 (Official Build) (64-bit)
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It just worked. I disabled the two flags
chrome://flags/#enable-experimental-web-platform-features
chrome://flags/#enable-web-bluetooth-new-permissions-backend
Restarted Chrome again, added in the token and it worked immediately.
Thanks @Rsava! I don't think it's related to the flags. Should you run into this error again, please send me the console log. There is almost certainly useful information in there. In the meantime I'll try to recreate this scenario myself.
Thanks @Rsava! I don't think it's related to the flags. Should you run into this error again, please send me the console log. There is almost certainly useful information in there. In the meantime I'll try to recreate this scenario myself.
Sorry, should have said "disabled the two flags, restarted Chrome, enabled the two flags", and it worked.
@Rsava: What did you imediately after you entered the token? You are supposed to press either tab or enter. Did you do anything else?
Hm. I still cannot reproduce the problem. I get this behavior when I paste the token incorrectly. Either incomplete or with extra characters. But knowing your profession @Rsava, I sincerely doubt that this was the case here.
Oh, it might have been the case. And when it finally worked, I pasted it correctly.
I am not one to say I cannot make mistakes; in fact, I have learned over the years that is usually the first place to look ... 
I am about to release version 4.2.1. Please be warned that on your first visit to chess.com after the update you will be requested to authorize Chessconnect to transmit moves in your name. This is required because Chessconnect now uses the official channels to interact with chess.com. After that you will be using Chessconnect with chess.com's blessing.
A huuuuuuge "thank you" goes to @Rsava for repeatedly nudging me towards this goal. For me this is an absolute milestone!
This is a major update and it has been thoroughly tested. But there might still be bugs. Just bear with me, let me know what does'nt work, and I will do my best to fix it.
This is required because Chessconnect now uses the official channels to interact with chess.com. After that you will be using Chessconnect with chess.com's blessing.
This is HUGE! A big win for @joernupbde and the Chessconnect extension.
A huge thank you to you, Jörn, for pushing to get this approved and for all of your work in making a piece of software that is so robust and handles so many boards.
A huge thank you to you, Jörn, for pushing to get this approved and for all of your work in making a piece of software that is so robust and handles so many boards.
Understatement of the year! Kudo's to all involved--impressive progress!
It is done. 4.2.1 is now the new official release. Let's hope that the update runs smoothly everywhere. I find it pretty scary to unleash something like this onto 1800 users. 
Took a little time but I got it to work with my board! It now works on the pc against humans and bots. Thank you!
@Tarkinz: That's great to hear. Why did it take you a little time? Maybe there is something I can improve?
I think it was mostly user error. I had trouble connecting the Bluetooth, but I think it was mostly because the board wanted to connect to my phone. I went through the steps on your website and it connected but wouldn't play. A full restart of the board fixed it and I was able to connect via the Chessconnect button. So like I said, most likely a user error as your website really helped to walk me through everything.
Awesome, @KNAVFAR! One more board ticked off my list.