TVS-1271U-RP Loss of AD Connection after 4.3.3 Upgrade

[Bandit51]

I recently upgraded one of my QNAP 1271U-RP from 4.2.X to 4.3.3 and after reboot I could no longer pull any domain users or groups (Win Server 2012R2) getting a "Connection Timeout" error. I've split the 68TB storage up between Veeam backups (ISCSI connection) and network share backups (Windows Share). The ISCSI connection was fine but the Share was un-reachable so that told me that something happened during the upgrade to my AD connection which I'm not sure if anyone has had this issue or not but thought I'd ask (I could not get to share by IP or FQDN asked for credentials; could ping QNAP tho). I have a 2nd 1271 that holds all of my organizations network shares and now am very hesitate to upgrade the firmware on it as it holds multiple tiers of permissions using AD integration with groups/users and would be a mess if I had to redo my perms. This is the first time I've had this happen doing a firmware upgrade with my QNAPs, thanks.

[iok]

I have experienced the same issue upgrading to 4.3.3.
The only solution I have found is to disable domain authentication e then re-enable it, re-joining the domain.
This is a bit annoying because you could loose all the permission assigned to domain groups or users for the NAS shares, but it works.
I guess that the Samba upgrade break the association with the domain computer object.

[brute4ce]

Same here.
Fixed via unjoin/join Domain member and manually setting all permissions again as mentioned before.

[omnislash]

I'm having this issue also. Ive had it in the past with other firmwares but this is been more persistent. Using the local NAS accounts it works fine, or in my case using the IP address works which is strange. I'm going to reboot and see if that fixes the issue. It seems the NAS isn't talking to the domain controller properly. There must be a way to reconnect it without rebooting or disconnect/reconnect each time?