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How to analyze UniFi Network bottlenecks using DPI and traffic stats

Slow networks are frustrating. When bandwidth flags under load, most admins guess the cause. But UniFi’s DPI and traffic stats give clear answers. They show what’s using data, who’s using it, and when. Armed with those insights, you can fix issues instead of guessing.

Let’s dive in  !!

Before we dive in, please don't self-host your UniFi Controller if you take care of client networks. Sooner or later this will cause issues! It's fine for home users, but definitely not recommended for IT service businesses and MSPs. If you want secure, reliable and a scalable hosting solution check out UniHosted. )

1. Start with DPI: a deeper view into traffic

DPI (Deep Packet Inspection) tells you what kind of traffic flows through your network. It's not about content, just the type of data: video, gaming, backup, VoIP, and more. Here’s what you do:

  • Go to Settings → System → Advanced and enable “Traffic & DPI”
  • In the dashboard, watch the Security or Traffic insights panel
  • You’ll see top applications by volume, plus per-client breakdowns

This gives you visibility into the biggest bandwidth users. A sudden spike? DPI reveals whether it’s video streaming, backups, or updates causing it.

2. Check total throughput vs. ISP speed

Open Insights → Traffic Stats to view real-time bandwidth. Compare:

  • Your total usage (upload/download)
  • Your ISP plan speed

If you never hit your plan’s full speed even with DPI disabled, the issue may be your ISP or modem. But if you hit or exceed that speed under peak load, it points to internal bottlenecks like gateway CPU or LAN limits.

3. Identify the top talkers

Under the DPI dashboard, find “top clients” listed by traffic volume. Drill into each:

  • See which devices are heavy hitters
  • Check what apps or services they’re using
  • Note time windows of peak usage

Once you identify the heavy device, you can address it directly, maybe a backup system or a gaming console hogging bandwidth.

4. Check for gateway CPU and DPI burden

On UniFi gateways, especially older USG models, DPI and IDS can hit performance hard.

  • Visit Settings → Gateway to see CPU load
  • Look for gateway performance hitting limits, especially under DPI
  • If CPU is high during traffic bursts, DPI may be causing the slowdown

Many admins find turning off DPI and IDS on old gear restores speed. Or you can move DPI to a more modern UDM or UDR model for better handling.

In Traffic Stats, shift filters to “By hour” or “By day”:

  • Is traffic peaking during business hours?
  • Are uploads (backups) happening at night?
  • Monitor trends across weeks

Time-based patterns help you schedule heavy tasks more wisely or throttle traffic during peak hours.

6. Troubleshooting typical scenarios

Here are common issues and how to tackle them:

Scenario A: Bandwidth peaks but gateway maxes out

Cause: Intense DPI or IDS load on hardware-limited gateways. Fix: Disable DPI/IDS on USG; move to UDM‑Pro if full protection matters.

Scenario B: One device hogs all bandwidth

Cause: Large syncs, torrent, or streaming running on a client. Fix: Apply per-client throttling in Settings → Traffic Rules, or schedule the task outside business hours.

Scenario C: Traffic bursts in a specific time window

Cause: Scheduled updates, backups, cloud sync. Fix: Reschedule to off-hours or add bandwidth caps during rush periods.

Scenario D: Slowdowns only at certain times of day

Cause: Local network saturation or ISP throttling. Fix: Monitor ISP speed and compare with internal traffic; adjust QoS or consider upgrade.

7. Traffic rules: throttle, block, or prioritize

In Settings → Traffic & QoS, implement rules such as:

  • Limit access to backup or streaming apps during the day
  • Block torrent/bit‑torrent entirely on guest networks
  • Prioritize low‑latency apps like VoIP or gaming
  • Segment backup traffic into a separate VLAN or gateway queue

These rules help you manage bandwidth based on DPI insights instead of guesswork.

8. Use VLANs and network segmentation

Create separate networks for:

  • Staff – Normal usage, no restrictions
  • Guests – Bandwidth-limited and isolated
  • Backups/Servers – Schedule or restrict them
  • POS/IoT – Isolated traffic, secure

Set unique SSIDs and VLAN IDs, ensuring DPI stats report separately and enforcement remains granular.

9. Upgrade hardware strategically

If DPI on older gear is maxing out, upgrading pays off:

  • Replace UniFi Security Gateway with UDM‑Pro or UDR
  • Use multi-gig switches to avoid LAN bottlenecks
  • Add APs and switches incrementally as your network grows

Even one UDM‑Pro can handle DPI at gigabit speeds, clearly better than older gateways.

10. Monitor long-term for consistency

Don’t just respond to a one-off spike. Use the stats dashboard for trends:

  • Set monthly resets to avoid bloated metrics
  • Note slowdowns that reappear daily or weekly
  • Track bandwidth hungry apps, like Zoom or updates, over time
  • Archive monthly reports to support upgrade or policy decisions

Long-term trend watching helps you plan bandwidth budgets and network refresh cycles.

11. Set alerts and logs

In Settings → Alerts, configure:

  • High gateway CPU load
  • Interface overload
  • Top AQ apps hitting threshold
  • Device offline or disconnected

Receive notifications via email or mobile for fast fix action.

12. Educate your users

Your network is as good as its rules. Make sure you:

  • Announce bandwidth policies clearly via staff email or signage
  • Explain why backups or large uploads bear limits
  • Be transparent about prioritizing business-critical apps
  • Reinforce the need by sharing occasional traffic reports or stats

When policies make sense, users see value instead of frustration.

13. Case study: how DPI helped solve a slowdown

A small office complained of slow internet around 10 PM daily. DPI showed all bandwidth was going to “CloudBackup” from a NAS. Gateway CPU peaked.

Fix:

  • Scheduled backups to 2 AM
  • Throttled uploads to backup servers by capping backup traffic
  • Setup VLAN for backup traffic so it didn’t affect staff Wi‑Fi
  • After changes, daytime bandwidth was restored and backups still completed with no interruptions

14. When DPI isn’t enough

There are scenarios DPI can’t solve:

  • Encrypted traffic makes app detection harder
  • Inter-VLAN LAN transfers don’t show in WAN stats
  • Router-based NAT floods or broadcast storms won't be visible in DPI

Use tools like packet captures or spectrometers alongside DPI to diagnose complex LAN issues.

15. Best practices summary

  • Always enable DPI on modern UniFi gateways
  • Compare real-world vs. rated ISP speeds
  • Track top applications, match them to policies
  • Check gateway CPU to see if DPI is the issue
  • Schedule heavy traffic off-peak
  • Use VLANs to isolate backup/server traffic
  • Upgrade hardware when gateway performance flags
  • Monitor trends and reset stats monthly
  • Set alerts for anomalies
  • Explain policies to users, traffic optimization is for everyone's benefit

16. Final thoughts

UniFi DPI and traffic stats are powerful tools, well beyond a simple usage meter. They empower you to see who’s using your network, what they’re doing, and when.

If you manage clients or guest networks, hosting your controllers through Unihosted gives you reliable, always-updated DPI features and alerting across sites. You stay ahead of bottlenecks, not chasing them during performance dips.