QoS vs SQM

QoS vs SQM

Which Mode Should You Choose?

Choose QoS if you have:

• Multiple VLANs or SSIDs with different needs
• WAN upload bandwidth to prioritize
• Need hard caps per network segment
• Tailscale mesh traffic that needs priority

Best for: "LAN has priority over Guest during video calls"

Choose SQM if you have:

• Single WAN connection with bufferbloat issues
• Simple home network without VLAN priorities
• Want automatic queue management
• Need fairness across all devices

Best for: "I want my uploads to not choke my download"

---

Technical Differences

Feature	QoS Mode	SQM Mode
Architecture	WAN-rooted HTB + per-VLAN classes	Single WAN CAKE qdisc
Priority Classes	LAN > IoT > Guest	All traffic equal (flow-based)
Upload Shaping	Hard cap + priority	CAKE handles automatically
Download Shaping	Via bridge-level shaping	Not implemented
Tailscale Priority	Yes (highest)	No
nft Classification	Yes (fwmark → tc fw filter)	No
Use Case	Multi-VLAN, business	Home, bufferbloat

---

Implementation

QoS Mode

WAN egress (eth0): HTB root
├── Class 1:10 LAN/tailscale (prio 1) [+ bridge shaping]
├── Class 1:20 IoT (prio 2)
├── Class 1:30 Guest (prio 3)
└── nft marks steer traffic to classes

SQM Mode

WAN egress (eth0): CAKE diffserv
- Automatic flow isolation
- CoD (Connection-Oriented Data) prioritization
- Built-in fq_codel algorithm