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Slower data transfer during file uploads to a NAS device

Slower data transfer during file uploads to a NAS device

N
Nacheey
Junior Member
22
08-10-2025, 11:03 AM
#1
Hello everyone! I'm dealing with a problem that needs some fixing... When moving files, my connection is slow (about 40MB/s) over a GIG-e link to the NAS. The PCs have two drives, both using different Windows 11 versions—one for WAN and one for LAN only. On the LAN-only drive, I see 100MB/s speeds. It seems like the hardware itself isn't the problem.

There are seven devices on this network; two are affected. The affected ones include the PCs with the two partitions (newer Windows) and a laptop. Both use Windows 11 26100. The other systems run Windows 22.631, which is older.

In Task Manager, the LAN-only drive shows only 30% usage during file transfers, while the WAN side stays at 100% with faster speeds. When I test the WAN speed on another device, it comes back to 950MBps. Sharing folders via Windows Explorer LAN folder works fine, but when sending files from an affected system to an unaffected one, speeds jump to 110MB/s. The NAS is mounted as a drive letter using its IP address in File Explorer.

I suspect the issue started after updating to Windows 26100. I've tried reinstalling network adapters on both sides, disabling antivirus/firewall, and even changing IP settings. I also reset the NAS, but nothing changes. The problem seems tied to Windows 26100, though it works perfectly when transferring at full speed from a healthy system.

I've checked all background apps, disabled auto-tuning profiles, and adjusted network settings, but it still doesn't resolve. Any suggestions? Thanks in advance!
N
Nacheey
08-10-2025, 11:03 AM #1

Hello everyone! I'm dealing with a problem that needs some fixing... When moving files, my connection is slow (about 40MB/s) over a GIG-e link to the NAS. The PCs have two drives, both using different Windows 11 versions—one for WAN and one for LAN only. On the LAN-only drive, I see 100MB/s speeds. It seems like the hardware itself isn't the problem.

There are seven devices on this network; two are affected. The affected ones include the PCs with the two partitions (newer Windows) and a laptop. Both use Windows 11 26100. The other systems run Windows 22.631, which is older.

In Task Manager, the LAN-only drive shows only 30% usage during file transfers, while the WAN side stays at 100% with faster speeds. When I test the WAN speed on another device, it comes back to 950MBps. Sharing folders via Windows Explorer LAN folder works fine, but when sending files from an affected system to an unaffected one, speeds jump to 110MB/s. The NAS is mounted as a drive letter using its IP address in File Explorer.

I suspect the issue started after updating to Windows 26100. I've tried reinstalling network adapters on both sides, disabling antivirus/firewall, and even changing IP settings. I also reset the NAS, but nothing changes. The problem seems tied to Windows 26100, though it works perfectly when transferring at full speed from a healthy system.

I've checked all background apps, disabled auto-tuning profiles, and adjusted network settings, but it still doesn't resolve. Any suggestions? Thanks in advance!

A
Asssure
Member
56
08-10-2025, 11:03 AM
#2
Many effective troubleshooting steps have been completed here. Strong effort was shown. Please try booting a Linux live USB on both the impacted and unaffected systems to compare results. This will help determine if the issue lies with hardware or software. You mentioned testing large file transfers (>1GB), which is accurate since such operations tend to be slower. Also, monitor disk usage and CPU utilization per core during transfers using Task Manager (Performance > CPU > right-click graph > change graph to logical processors) while the transfer is in progress.
A
Asssure
08-10-2025, 11:03 AM #2

Many effective troubleshooting steps have been completed here. Strong effort was shown. Please try booting a Linux live USB on both the impacted and unaffected systems to compare results. This will help determine if the issue lies with hardware or software. You mentioned testing large file transfers (>1GB), which is accurate since such operations tend to be slower. Also, monitor disk usage and CPU utilization per core during transfers using Task Manager (Performance > CPU > right-click graph > change graph to logical processors) while the transfer is in progress.

D
DarkTiger427
Member
186
08-10-2025, 11:03 AM
#3
No, I don't use VLANs.
D
DarkTiger427
08-10-2025, 11:03 AM #3

No, I don't use VLANs.

T
tomoyan1441
Member
58
08-10-2025, 11:03 AM
#4
Reinstalling drivers for Windows 10 is a common fix. Also, check for updated cables or switches if needed.
T
tomoyan1441
08-10-2025, 11:03 AM #4

Reinstalling drivers for Windows 10 is a common fix. Also, check for updated cables or switches if needed.

D
DeadPool6543
Junior Member
37
08-10-2025, 11:03 AM
#5
It's challenging to diagnose this situation. I'm focusing on software rather than hardware. The network performance remains slow across both operating systems in my dual-boot setup. Despite reinstalling drivers and testing various switches, the issue persists without any hardware changes.
D
DeadPool6543
08-10-2025, 11:03 AM #5

It's challenging to diagnose this situation. I'm focusing on software rather than hardware. The network performance remains slow across both operating systems in my dual-boot setup. Despite reinstalling drivers and testing various switches, the issue persists without any hardware changes.

L
Le_Conteur
Junior Member
49
08-10-2025, 11:03 AM
#6
The most problematic issue... it's a software problem. Those take a long time to resolve.
L
Le_Conteur
08-10-2025, 11:03 AM #6

The most problematic issue... it's a software problem. Those take a long time to resolve.

B
Bddit95
Member
64
08-10-2025, 11:03 AM
#7
It seems possible the issue occurs in a WSL setup. The update might have disrupted network transfer protocols. You can revert to a previous restore point before the Windows update.
B
Bddit95
08-10-2025, 11:03 AM #7

It seems possible the issue occurs in a WSL setup. The update might have disrupted network transfer protocols. You can revert to a previous restore point before the Windows update.

G
GabePlayzZ
Junior Member
8
08-10-2025, 11:03 AM
#8
I'm able to handle it, though it takes a lot of time. These days are hectic, so maybe I'll finally tackle it. It's a challenging task.
G
GabePlayzZ
08-10-2025, 11:03 AM #8

I'm able to handle it, though it takes a lot of time. These days are hectic, so maybe I'll finally tackle it. It's a challenging task.

_
_zNinjaa_
Member
132
08-10-2025, 11:03 AM
#9
It appears that following a random Windows update, performance returns to normal on impacted devices. My thoughts are getting a bit jumbled!
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_zNinjaa_
08-10-2025, 11:03 AM #9

It appears that following a random Windows update, performance returns to normal on impacted devices. My thoughts are getting a bit jumbled!

X
xXFirewitherXx
Posting Freak
878
08-10-2025, 11:03 AM
#10
I experienced a network adapter that would completely crash the network stack after a Windows Update. After using onboard for several years, I tried it again by chance and it now functions properly. I’m unsure what Microsoft is doing with the network stack—it feels quite unusual to me. Even when it works, I don’t believe Windows 11 provides consistent performance across machines on my LAN compared to Linux.
X
xXFirewitherXx
08-10-2025, 11:03 AM #10

I experienced a network adapter that would completely crash the network stack after a Windows Update. After using onboard for several years, I tried it again by chance and it now functions properly. I’m unsure what Microsoft is doing with the network stack—it feels quite unusual to me. Even when it works, I don’t believe Windows 11 provides consistent performance across machines on my LAN compared to Linux.