Unable to connect with F2-421

[Rajesh]

All was working fine. I tried to map a network drive, but couldnt. The TNAS started to slow in UI so I restarted, from then on I am not able to connect with the TNAS in any means.

Here is my setup.
1. TNAS connected to the ATT Router.
2. Firewall is disabled.
3. Laptop&Mobile in the same network as the TNAS.
4. No Network proxy settings.
5. From TNAS PC app couldn't discover the TNAS at all.
6. From TNAS mobile app also couldn't perform backup.
7. LAN light and HDD lights are blinking.

I even tried removing both the Hard drives and after restart the LAN link is blinking green. But unable to discover the TNAS.
Please help me to restore the TNAS.

[Rajesh]

The IP address is visible from the ATT router and shows the device is up and running.
When using the Advanced port scanner in windows it shows a different IP address for the same MAC.
But both address doesn't take me to the TOS page.

[TMzethar]

What is the TOS version?
Do you remember the actions taken before the problem occurred?

[TMzethar]

We have observed that your TNAS model is commonly used during the TOS4 period. Please confirm if you are currently experiencing this issue:
viewtopic.php?f=28&t=4912

[Rajesh]

I don't remember the TOS version it was updated a month back.
Last action was mostly on laptop emabling SMB and not on ToS.

[Rajesh]

I remember having seen this message. So should be TOS 5.1

Earlier TOS versions cannot be directly updated to TOS 5.1, and must be manually updated step by step in the following order: 5.0.120 -> 5.0.176 -> 5.1.24 -> 5.1.40（Or newer TOS version）

[TMzethar]

You can refer to this to confirm the status of the device and tell us the result of your attempt.
We will provide some possible feasible suggestions based on the information you provide.
viewtopic.php?f=82&t=4837
Can you access with SSH/Telnet when you start TNAS as an empty device? (with no disk in it.)