[Help] Low file copying speed over the network

[protogonist]

Hello to all.Initially, the NAS was connected to the mesh point via a cable, and the PC was also connected to the same point via a cable. The file copying speed from the PC to the NAS was similar to that of an internal hard drive (120–150 MB/s). Then I moved the NAS to another room, and now it is connected via a cable to another mesh point. Now the system looks like this: room 1, with a PC in it, connected via a cable to the mesh point. This mesh point is connected via WIFI to a second identical point, to which the NAS is connected via a cable, and to which the internet input cable is attached. The file copying speed does not exceed 300–600 kb/s. TNAS is installed latest, factory reset was performed. The network adapter in the PC was not changed; Windows was reinstalled. What should be checked to restore the speed? Thank you. Mesh system - Deco BE65 Pro, NAS - TMaster 425.

[EriChan]

Since your speed was normal (120–150 MB/s) when both devices were wired to the same node, the hardware and drive performance are healthy. A drop to 300–600 KB/s strongly indicates a network-level routing issue or a severe bottleneck in the wireless mesh link.

Here are the key points to check to identify and resolve the issue:

1. Verify Connection Method

• Local IP vs. Cloud ID: Ensure you are accessing the NAS via its local LAN IP address (e.g., \\192.168.2.xxx in Windows Explorer or browser).

• If you connect using DDNS or remote quick-connect tool, changing network points might cause the traffic to route out to the internet through an external relay server rather than staying local.

2. Check Ethernet Link Negotiation Speeds
When moving the cables, a bent pin or poor contact can cause the link to downgrade or suffer packet loss:

• On the NAS: Go to TOS > Control Panel > Network > Interface, and verify the physical connection status shows 1000 Mbps (or 2.5 Gbps) Full Duplex.

• On the PC: Open Windows Settings > Network & Internet > Ethernet (or Network Adapter Properties) to confirm the link speed is negotiated at 1000/1000 Mbps (or higher).

3. Check Deco BE65 Pro Mesh Backhaul & Settings

• Backhaul Signal Strength: Open the TP-Link Deco App and check the signal health between Node A and Node B. If the two nodes are too far apart or separated by thick walls, the wireless backhaul link may degrade significantly.

• Device Isolation / Guest Network: Make sure neither the PC nor the NAS was accidentally assigned to an IoT / Guest Network or has Client Isolation enabled in the router settings.

• QoS / Security Inspection: Temporarily disable QoS or HomeShield Antivirus / Intrusion Prevention features in the Deco app to test if deep packet inspection is throttling local inter-node traffic.

4. Test Raw Throughput via iperf3
To isolate whether the bottleneck is pure network throughput or SMB file transfer:

• Run an iperf3 throughput test between your PC and the NAS. If iperf3 also reports speeds in the KB/s range, the issue is purely the wireless link/routing between the two Deco nodes.

Please check the items above and let us know what you find!