The user experienced extremely slow file transfer speeds, around 100-200 megabits per second, despite having a 10 gigabit network setup. Initially, the user suspected the Unifi UNAS Pro 8 NAS, its RAID 6 configuration, or NVMe cache, as well as the Immich application. Troubleshooting steps like changing cache settings and stopping Immich yielded no improvement. The problem persisted even after ruling out the NAS by performing an iperf3 test between the desktop and a miniPC.This direct network test revealed an asymmetrical speed issue, with download speeds being very low and upload speeds significantly better but still not optimal. Examining the Intel NIC statistics showed a high number of discarded packets. The user increased the receive buffer size on the NIC, which eliminated discarded packets in one direction but didn't fully resolve the speed issue.The breakthrough came when disabling Large Send Offload (LSO) V2 for IPv4 on the Intel NIC. This single change dramatically increased the download speed from 313 megabits per second to 7.03 gigabits per second. LSO is designed to reduce CPU load by letting the NIC handle packet segmentation, but in this specific configuration, it was hindering performance. After this adjustment, real-world file copy speeds to the NAS improved significantly to approximately 350 megabytes per second, or 2.8 gigabits per second. The key takeaway is that when facing storage performance issues, it's crucial to isolate the network and test it independently, as sometimes network adapter settings like LSO can be the bottleneck.