[Help] TOS UPS Network (TNAS UPS server) client configuration will not save on second NAS – UI + SSH both blocked

[HeatherC]

Hello,
I’m looking for guidance on configuring UPS network shutdown between two TerraMaster NAS devices, as I appear to have hit a limitation or bug in TOS.
My setup

Hardware:
UPS: CyberPower CP1600EPFCLCD-UK
NAS 1 (UPS master): F5-422
- Connected to UPS via USB
NAS 2 (UPS client): F4-424 Pro
- Both NAS units are on the same LAN and both devices running TOS version 6.0.794
- Router + modem are also on the UPS

UPS outlets:
Battery + Surge:
- F5-422
- F4-424 Pro
- Router
- Modem

Goal:
Have the F5-422 act as the UPS master and the F4-424 Pro shut down cleanly as a network UPS client when the UPS reports a power failure.

What works correctly
On the F5-422:
- Control Panel → Hardware & Power → UPS
- UPS Type: USB UPS
- UPS is detected correctly
- “Set TNAS as a network UPS server” enabled
- F4-424 Pro IP added as an allowed client
- Apply works and settings persist

The F5-422 behaves exactly as expected.

The problem (F4-424 Pro)
On the F4-424 Pro, attempting to configure it as a UPS client fails.

UI behaviour:
- Control Panel → Hardware & Power → UPS
- Enable UPS support ✔
- UPS type: TNAS UPS server
- UPS server IP: F5-422 IP (e.g. 192.168.0.169)
- Waiting time: Sync with server

However:
- The UPS server IP field always shows a red border
- Apply either:
- Does nothing, or
- Allows navigation away but shows “changes not saved”
- Returning to the page shows all settings lost
- No error message is displayed

I also tried the example format shown in the UI (http://ip:port) but that also fails

What I tried via SSH (advanced troubleshooting)
I attempted to bypass the UI and configure the UPS client manually using NUT:
- /etc/nut exists and contains standard files (nut.conf, upsmon.conf, etc.)
- sudo id confirms I have root (uid 9999)
- However:
- /etc/nut/nut.conf is not writable, even with sudo
- sudo sh -c 'echo ... > /etc/nut/nut.conf' → Permission denied
- /usr/local/etc cannot be created either (Permission denied)
- Root shell (sudo -i) is not permitted on TOS (expected)

This suggests:
- The UPS/NUT configuration paths are hard-locked on this TOS build
- The UI also cannot persist TNAS UPS client settings
- There is currently no supported way to configure a UPS client NAS

Current status
- F5-422 shuts down cleanly after UPS delay (works)
- F4-424 Pro remains on battery and will eventually hard-power-off if the battery is exhausted
- This is acceptable but not ideal, and defeats the purpose of “network UPS support”

My question
Is this a known limitation or bug in current TOS versions?
Specifically:
- Is there a supported way to configure a TNAS UPS client that actually persists?
- Is there an alternative path (config location, service, or setting) that the UI should be writing to?
- Or is network UPS shutdown between TerraMaster NAS devices currently not supported or broken on some firmware branches?
Thank you.

[Gremlin]

I have UPS Server set on Tos6 version and have checked "sync with server" option on Tos7 version and that does not present errors (not saying it works, but no setup error).

You may find some relevance here:
viewtopic.php?p=53312#p53312

[HeatherC]

I have UPS Server set on Tos6 version and have checked "sync with server" option on Tos7 version and that does not present errors (not saying it works, but no setup error).

You may find some relevance here:
viewtopic.php?p=53312#p53312

Thanks — I very much appreciate you responding to me. That aligns with what I’m seeing.
I’ve now tested on TOS 6.0.794 (which claims to fix UPS issues) on both an F5-422 and an F4-424 Pro, and the TNAS UPS client configuration still will not persist (UI or SSH).

For now I’m leaving one NAS as USB UPS master and relying on battery runtime for the second. Not ideal, espeicallly when it should be possible to have the F5-422 act as the UPS master and the F4-424 Pro shut down cleanly as a network UPS client when the UPS reports a power failure. Another annoying TOS quirk.

[ColaChen]

Hello,

1. First question: You mentioned that the results cannot be saved. Could this issue be caused by an incorrect format of the input content? If convenient, please provide screenshots of the interface operation errors.
2. Second question: Root cause of the TNAS UPS failing to maintain a persistent connection:
When the server-side device of the TNAS UPS is powered off or shut down, the client-side connection will switch to the disabled state. This is in line with the default design logic and is considered normal behavior.
If both devices are powered off simultaneously:
- If the TNAS UPS server device is turned on first, the client-side device will automatically detect and re-establish the connection.
- If the client-side device is turned on first and detects that the TNAS UPS server is unavailable, the connection status will display as disabled, and manual reactivation will be required.