QSync Client can find NAS but cannot connect to the QSync Service on it

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1

Met a strange problem.

Configuration:

  • PC: Windows 10 + Qsync Client 5.1.10.0918 (latest)
  • TS-551 with QTS 5.2.7.3256(2025/09/13)
  • QSync 5.0.0.3(20250828)
  • Both PC and NAS are in local home network

Issue:

  1. It worked before: the Qsync Clint in Windows can connect to QSync service on the NAS.
  2. At some point (~ 1 week ago), it shows “fail to connect”.
  3. I tried to discover NAS from QSync Client, the NAS can be found.
  4. But when I select the discovered NAS for connection, QSync Clientfails with error “invalid network address”
  5. I use Wireshark to capture network traffic with step #4 above, there is no traffic captured.
  6. I reinstalled QSync Client, same result.
  7. I disabled firewal on Windows 10, same result.
  8. I tried installing same QSync Client on another laptop, and it works well. So I assume the problem is not at NAS side.
  9. The local support guy sent me a beta version of QSync Client 6.0, it fails with the same error.

The local support guy cannot help further. He suggested me to upgrade Windows to Win 11 ……

Any suggestion are welcome.