# Debugging my new network, when 10 Gigabit Ethernet Runs at 300 Megabits

DevFeed: [Debugging my new network, when 10 Gigabit Ethernet Runs at 300 Megabits](<https://devfeed.tech/articles/debugging-my-new-network-when-10-gigabit-ethernet-runs-at-300-megabits-21852.md>)

Original publisher: [Read original article](<https://www.hanselman.com/blog/debugging-my-new-network-when-10-gigabit-ethernet-runs-at-300-megabits>)

Published: 2026-08-27T15:25:48Z

Content type: article

Language: en

Sources: [Scott Hanselman](<https://devfeed.tech/sources/scott-hanselman.md>)

Topics: [Homelab](<https://devfeed.tech/topics/homelab.md>), [debugging](<https://devfeed.tech/topics/debugging.md>), [UniFi UNAS Pro](<https://devfeed.tech/topics/unifi-unas-pro.md>), [intel](<https://devfeed.tech/topics/intel.md>), [Windows](<https://devfeed.tech/topics/windows.md>), [NVMe](<https://devfeed.tech/topics/nvme.md>)

Tags: [debugging](<https://devfeed.tech/tags/debugging.md>), [homelab](<https://devfeed.tech/tags/homelab.md>), [intel](<https://devfeed.tech/tags/intel.md>), [musings](<https://devfeed.tech/tags/musings.md>), [nvme](<https://devfeed.tech/tags/nvme.md>), [smb](<https://devfeed.tech/tags/smb.md>), [ssd](<https://devfeed.tech/tags/ssd.md>), [storage](<https://devfeed.tech/tags/storage.md>), [unifi-unas-pro](<https://devfeed.tech/tags/unifi-unas-pro.md>), [windows](<https://devfeed.tech/tags/windows.md>)

## AI overview

A Windows desktop connected to a 10GbE homelab network was limited to roughly 100-200 megabits per second despite 10-gigabit link indications. Direct testing traced the problem to the Windows/NIC path: increasing the Intel E610 driver's receive buffers eliminated discarded packets and improved receive throughput, while disabling IPv4 Large Send Offload V2 raised transmit throughput to 7.03 Gbit/sec.

## Source excerpt

I've been moving my home storage over to a UniFi UNAS Pro 8 as part of a larger homelab moderization. My main IRONHEART (the ultimate PC from a few years back) desktop now has an Intel E610-XT2 10GbE card, the NAS is on 10GbE, and there's a Minisforum MS-01 miniPC on the same network with a 10GbE SFP+ connection running Immich and Portainer and a few other things. Everything says 10 gigabit. Windows says 10 gigabit. UniFi says 10 gigabit. SMB copies are using the correct NIC but my file copies are running at around 100 to 200 megabits per second which is sad making. Naturally, I blamed the NAS, and the spinning rust within. The UNAS has six 16 TB spinning disks in RAID 6 and a pair of NVMe SSDs being used as cache. I'm also running Immich on the MS-01, with its photo library living on the UNAS, so there are lots of thumbnails, metadata reads, and little background writes happening. All seem like reasonable suspects. I switched the UNAS SSD cache from read-write to read-only. No meaningful difference. I stopped Immich completely. No difference. I looked at iostat; the disks weren't saturated. We looked at SMB signing and Windows Defender network scanning. Still slow. Then I stopped testing the NAS and ran iperf3 directly between the Windows desktop and the MS-01: iperf3 -c 192.168.1.222 -P 4 133 Mbit/sec Oops. The reverse test was better, but still wrong: iperf3 -c 192.168.1.222 -P 4 -R 1.33 Gbit/sec That's weird. Now the disks, SMB, Immich, RAID, and the NAS itself were completely out of the equation. This was a Windows/NIC problem and it's weirdly asymmetrical. Looking at the Intel adapter statistics shows me... Get-NetAdapterStatistics -Name "Ethernet - 10 Gig Intel" There were nearly a million ReceivedDiscardedPackets. During one ten-second iperf3 test, the counter increased by another 268. Why? The E610 driver had its receive buffers at the default 512, although it supported up to 4096. I increased them. I love an increased buffer. Set-NetAdapterAdvancedProperty