AD Authentication Failed after upgrade to 5.40 on USGFLEX700 model only

rv_faro

hi everybody,
after upgrading to ZLD 5.40 on USGFLEX700 (Standalone mode) we got systematic authentication failure using AD Authentication against windows server 2019 Domain Controllers (so this shouldn't have nothing to do with the Windows Server 2025's problem as of Zyxel's advisory of last April)
We've verified that on other models (e.g. USGFLEX500) AD authentication works fine.
We asked to some other companies we are in touch to and they confirmed to us that they had the same problem on USGFLEX700 model.
Now I'm in touch with support who are trying to deal with it.

Since I don't see anything about that problem in community i'd like to ask if there's anyone else who've got the same problem.

thank you all in advance for yr feedbacks.

Regards

Renato