Overview

SMB performance depends on both ends of the connection and the link between them. Start with health checks then apply targeted tweaks.

Prerequisites and checks

Confirm the basics first to avoid chasing symptoms.

• Update DSM, NIC drivers, and client OS
• Use wired links for heavy clients and verify link speed
• Check for duplex or flow control mismatches on switches

NAS SMB settings

Tune SMB where it matters and avoid overcomplication.

• Enable SMB signing only when required
• Use SMB 3 on current systems and disable legacy protocols unless needed
• Keep DNS and N T P correct to avoid auth delays

Windows client settings

A few changes improve browsing and copy speed.

• Map shares with DNS names and stable credentials
• Disable thumbnail generation on folders with very large media sets
• Use the latest NIC drivers and enable large send offload when stable

macOS client settings

Keep Finder responsive during large operations.

• Use smb://hostname connections and save to favourites
• Disable preview generation in large folders where practical
• Avoid third party antivirus scanning network paths in real time

Network path tuning

A clean path often beats any single setting.

• Adopt 2.5 GbE on NAS and primary desktops
• Use short quality cables and avoid daisy chained switches
• Set jumbo frames only when every device supports it end to end

Testing and validation

Measure before and after so changes are justified.

• Time a large file copy in each direction
• Test with a set of small files for metadata heavy workloads
• Record results and keep them with maintenance notes

Troubleshooting checklist

If speeds are inconsistent, look here first.

• Swap cables and ports to rule out physical issues
• Check switch logs for errors or negotiation changes
• Test a direct link from a PC to the NAS to isolate the switch

FAQs

Short answers for common SMB tuning questions.

• Will jumbo frames always help? Only when all devices support the same MTU
• Is antivirus the cause of slow copies? It can be, try excluding NAS paths
• Do I need 10 GbE? Use it when the entire path and workload justify it