QNAP TVS-872XT no longer visible on network

[John Harvey]

I hope this is the right place to ask. This is my first post here.

I recently bought a TVS-872XT and installed 8 Seagate Ironwolf 12TB NAS drives. I connected its 10Gbe LAN port back to a 10Gbe switch that also connects to my Windows 10 PC. The NAS fired up properly and was visible on my PC in Qfinder Pro and QTS.
I set up a Pool with RAID 10 selected. Took a long time to sync, but all good.
Once the Pool finished synching (took well over a day), I added a Volume that used almost all of the Pool capacity. That worked fine until I decided to remove the Volume so that I could choose different Volume values.
I also decided to remove the Pool and start again. While the pool was synching, I added a new Volume. Progress was very slow and often unresponsive.
I tried to stop the process, ultimately turning the NAS off to stop the process.
When I turned the NAS back on, the network couldn't find it. The IP address didn't work and Qfinder Pro couldn't find a NAS.
I tried a reset via the reset switch on the back of the unit. That didn't help.
I followed QNAP advice, turned the NAS off, removed the hard drives and turned the NAS back on. Qfinder Pro still couldn't find it.
The Status light is steady green, the LAN light is flashing yellow (orange?) and the drive status lights are all flashing green.

What can I try to get my NAS visible and working again? HELP!

[dolbyman]

what is the manufacturer date / serial number / board revision of the device?

viewtopic.php?f=50&t=153097

[John Harvey]

I solved the problem of my NAS no longer being visible on my network (shared / mapped network drive folders in Windows Explorer on my PC).
I reset the NAS (3 second push of the reset port on the back of the NAS).
I turned off devices in this order and turned them back on again in the opposite order:
- NAS, 10Gbe switch, PC, DHCP router

I had another problem of losing access again. I updated NAS firmware to the latest version.
That reset username and password to system default settings. Once I figured out what those settings were, I could log in via Windows network credentials.
I set up a new credential in Windows credentials using the NAS assigned name and password. I was then able to change the password to one of my choice.