Arena is absolute dogshit software and Wizards are ******* brain dead profit slaves. Absolutely useless company.

A few hours earlier was playing fine, after lunch, couldn't connect any more, i followed the troubleshooting and error continues, also on my mobile same error, already reboot my router.
Edit: i friend came and he can log with his account, after that, tryed again my my own acount and the "timeout"shows again

Experiencing the exact same issue.
I was playing a matchmade game, and in the moment I lost, I was disconnected and got this "Authentication failed ..." error.
What makes it more frustrating is the lack of acknowledgement from WoTC's side that this issue even exists.
I've uninstalled and re-installed a couple of times, performed a DNS flush and winsock reset, all to no avail.
Please fix ASAP

EDIT:
Works for me now, managed to log in on mobile (android).

I encountered this problem today. When I log in to the game, it shows "Authentic failed for username: Timeout". I tried many methods and still can't log in.

same error. tried everything that wizards of the coast suggested even flushing dns. nothing seems to work. tried logging in using windows/android/apple doesn't allow me to log in.. error: authentication failed.

Same issue, was playing no problem yesterday, closed the game, came back today and now I can't log in on any platform. Server page says fully operational and I was watching someone stream it earlier so it has to be either an account problem or a specific issue with a single server I would imagine. Super annoying.

grr

Mine is doing similar Unable to login "Failed deserialization...."

急にログインが出来なくなりました。パスワード編集画面で再設定を行う途中でコードを聞かれましたがコードを知りません。

I have uninstalled and reinstalled it 2 times and the error persists.

Since October, the frequency of these error messages has increased. Repeatedly logging in and out doesn't help. Please respond as soon as possible.

Having this issue right now as well - can't get in on any platform.

Having this issue right now.

same

Ssme thing since update. Cool that in this update was "Fixed a bug that could block logging in with a spurious "Authentication Failed" and/or "Attach Failed" message"...

Help please. PLease compensate my gold T_T

This issue started today after latest update.

RECEIVING THIS MESSAGE EACH TIME I TRY TO LOGIN..

I had this problem starting late last week. Previous times I saw the issue have usually been due to the server being down, and fixed simply by waiting less than a day. This time was different, and I and an acquaintance tried half a dozen devices over 5 days. Those with Windows 10 failed every time, including after trying every troubleshooting option suggested by Wizards Support. All devices with other OS were fine.

Our eventual solution: use prior version of the Arena launcher, which can be found in older versions of the installer (we used one from 2020 that had been saved way back then). We ended up downloading a 5GB update, and it had a few other issues, but it played perfectly.

Authentication failed for (username)
Timeout 14-1 -2022