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📖 DHCP Troubleshooting

A Technical Reference for Support Engineers

1. Why This Matters for eero Support

DHCP (Dynamic Host Configuration Protocol) is responsible for assigning IP addresses to devices when they join the network. When DHCP fails, devices cannot connect, communicate, or access services—even if Wi-Fi signal strength is excellent.

Understanding DHCP troubleshooting is essential because:

  • Device connectivity issues often stem from DHCP failures
  • Pool exhaustion causes new devices to fail silently
  • IP conflicts create intermittent connectivity problems
  • APIPA addresses (169.254.x.x) indicate DHCP breakdown

This document covers:

  • How DHCP works on eero gateway
  • Common failure scenarios and identification methods
  • IPv4 Reservations vs. dynamic assignment
  • Pool exhaustion detection and resolution
  • Real ticket patterns for Support Engineers identification

2. How DHCP Works on eero

DHCP Lease Process (DORA)

Step Process Description
D Discover Client broadcasts "DHCP DISCOVER" to find available servers
O Offer Server responds with "DHCP OFFER" proposing IP address
R Request Client requests the proposed address via "DHCP REQUEST"
A Acknowledge Server confirms with "DHCP ACK" and leases the address

Default eero DHCP Settings

Setting Default Value Notes
Subnet Range 192.168.4.0/22 192.168.4.0 – 192.168.7.255 (Main Network)
DHCP Pool Start .20 First 19 addresses reserved
DHCP Pool End .240 Usable range: .20 – .240
Total Usable Addresses 221 addresses Per /24 block (adjusts with custom subnets)
Lease Time 24 hours Default renewal interval
Gateway Address .1 eero gateway IP (usually 192.168.4.1)

IPv4 Reservation vs. Dynamic DHCP

Feature IPv4 Reservation Dynamic DHCP
Address Stability Always same IP Changes on lease renewal
Use Case Servers, printers, cameras Consumer devices (phones, tablets)
Configuration Manual in app Automatic
Impact on Port Forwarding Required for port forwarding Not compatible with port forwarding
Pool Deduction Still deducts from pool count Deducts from pool count

3. Common DHCP Failure Scenarios

Scenario A: APIPA Address Assignment (169.254.x.x)

Symptom Finding Diagnosis Resolution
Device shows 169.254.x.x APIPA address detected DHCP request failed Check physical connection, restart device, verify eero DHCP status

What is APIPA?

  • Automatic Private IP Addressing (RFC 3927)
  • Assigned when DHCP server is unreachable
  • Indicates Layer 2/Layer 3 connectivity issue between device and eero
  • Range: 169.254.0.0/16 (169.254.0.0 – 169.254.255.255)

Troubleshooting Steps:

  1. Verify device is connected to correct SSID
  2. Restart device's network adapter
  3. Check eero gateway status in app
  4. Power cycle eero if necessary
  5. Verify DHCP pool not exhausted

Scenario B: DHCP Pool Exhaustion

Symptom Finding Diagnosis Resolution
New device won't connect Old devices working DHCP pool full at capacity Expand DHCP range or remove stale reservations

Detection Method:

Step Action What to Look For
1 Count connected devices In eero app under Devices
2 Check DHCP pool size Settings > Advanced Networking > Reservation & Port Forwarding
3 Calculate availability Total pool (221 per /24) minus reservations
4 Compare If devices ≈ available addresses → exhaustion likely

Solution Options:

  1. Expand DHCP Range (if using /22 subnet, increase pool end to .250)
  2. Reduce Lease Time (force faster cleanup of inactive devices)
  3. Remove Stale Reservations (cleanup old device entries)
  4. Split Across SSIDs (use Guest Network to distribute load)

Scenario C: IP Address Conflict

Symptom Finding Diagnosis Resolution
Intermittent connectivity Error message mentions IP conflict Two devices claim same IP Identify conflicting device, enforce IPv4 reservation

Causes:

  • Static IP configured manually on device outside DHCP range
  • DHCP server assigned address already in use
  • Multiple DHCP servers on network (routers, extenders)

Resolution Steps:

  1. Disconnect one device and test connectivity
  2. Check for manually configured static IPs
  3. Enable IPv4 reservation for affected device
  4. Ensure only eero provides DHCP (no secondary routers)

Scenario D: Lease Renewal Failure

Symptom Finding Diagnosis Resolution
Device disconnects periodically Works initially then fails Lease renewal timeout Reduce interference, check eero signal strength, adjust lease time

Common Causes:

  • Weak Wi-Fi signal during renewal window
  • eero reboot during lease expiry
  • Interference disrupting renewal packets

Best Practices:

  • Ensure strong signal (> -65 dBm RSSI)
  • Maintain stable eero uptime
  • Use IPv4 reservation for critical devices

4. IPv4 Reservations (Recap)

When to Use IPv4 Reservations

Device Type Recommendation Reason
Printers ✅ Reserve Static addressing needed for discovery
Servers (file/game) ✅ Reserve Port forwarding requires stable IP
Security Cameras ✅ Reserve Remote access depends on consistent IP
Smart Home Hubs ✅ Reserve Automation requires stable network presence
Phones/Tablets ⚠️ Optional Dynamic assignment usually sufficient
Laptops ❌ Don't Reserve Mobility makes static IP unnecessary

Creating IPv4 Reservation (Step-by-Step)

Step Action Location
1 Open eero app Android/iOS mobile or tablet
2 Navigate to Settings > Advanced Networking > Reservation & Port Forwarding Network settings
3 Click '+' 'Add a reservation' button Middle of screen
4 Select "Enter Manually" Option presented
5 Enter Nickname, IP Address, MAC Address Form fields
6 Save and confirm Submit button

Important: IPv4 reservation ensures device always gets the same IP from DHCP pool. This is required for port forwarding to work reliably.

5. Real Ticket Scenarios

Scenario 1: "New Smart Bulb Won't Connect After Setup"

Investigation Finding Resolution
Check bulb IP 169.254.12.34 (APIPA) DHCP failed
Check connected devices 218 devices (pool near max for /24) Pool exhaustion
Check DHCP pool 192.168.4.20-240 221 addresses available
Action Expand DHCP range to .250 or move some devices to Guest Network Restore pool capacity

Scenario 2: "Printer Found Yesterday, Now Can't Print"

Investigation Finding Resolution
Check printer IP 192.168.4.55 then 192.168.4.62 IP changed after lease renewal
Check IPv4 reservation None configured Dynamic DHCP caused change
Check print queue Jobs failing due to IP mismatch Printers lost connectivity
Action Create IPv4 reservation for printer Ensure consistent IP address

Scenario 3: "Camera Offline Every Morning at 6 AM"

Investigation Finding Resolution
Check camera IP Consistently 192.168.4.100 IPv4 reservation working
Check eero logs Reboot occurring at 5:55 AM Scheduled maintenance
Check lease time 24 hours default Renewal coincides with reboot
Action Disable scheduled maintenance or adjust reboot time Prevent disruption during renewal

Scenario 4: "Guest Can't Get Internet on Phone"

Investigation Finding Resolution
Check phone IP 192.168.4.150 Main network, not Guest
Check SSID connection Connected to Main, not Guest User error
Check Guest Network Active and functional Working correctly
Action Guide guest to connect to Guest SSID Proper network separation

6. Common Pitfalls & Misconceptions

Misconception Reality Correction Strategy
"All devices need static IPs" Dynamic DHCP is fine for most Reserve only servers/devices needing port forwarding
"More devices = slower internet" Excess devices exhaust DHCP pool Monitor pool utilization, expand subnet if needed
"APIPA means hardware failure" APIPA indicates DHCP failure Check network connectivity first
"Reserving IP removes it from pool" Reserved IPs still count toward pool limit Account for reservations when calculating capacity
"Lease time doesn't matter" Shorter leases = faster cleanup Adjust based on network dynamics
"Guest Network shares Main pool" Guest Network has separate subnet Each SSID = independent address space

7. Quick Reference Card

DHCP Status Checklist

1. Check device IP → Is it 169.254.x.x (APIPA) or valid private IP?
2. Check pool utilization → How many devices vs. available addresses?
3. Check IPv4 reservations → Are critical devices reserved?
4. Check lease times → Is renewal causing disconnections?
5. Check SSID → Is device on correct network (Main vs. Guest)?

APIPA Troubleshooting Flow

Device has 169.254.x.x address
 ↓
Is device physically connected to SSID?
↓ No → Reconnect to correct network
↓ Yes
Can device ping gateway (192.168.4.1)?
↓ No → Layer 2 issue (check signal, interference)
↓ Yes
Can eero ping device?
↓ No → Device firewall blocking
↓ Yes
Is DHCP pool exhausted?
↓ Yes → Expand pool or remove stale reservations
↓ No
Restart device network stack

Pool Capacity Planning

Subnet Usable Hosts Typical Use Case
/24 254 (221 DHCP) Standard home (<100 devices)
/23 510 (~470 DHCP) Large home (200-400 devices)
/22 1022 (~990 DHCP) Estate/business (500+ devices)

Note: Actual DHCP pool may be smaller based on start/end configuration. Always verify in eero app settings.

DHCP Lease Time Guidelines

Network Type Recommended Lease Time Reason
Static-heavy (business) 24 hours Fewer renewals, stable devices
Dynamic-heavy (home) 12 hours Faster cleanup of transient devices
Guest network 4 hours Short-term visitor access
IoT network 24 hours Stable smart home devices

8. Related Documents in This Capstone Series

Document # Title Purpose
1A IPv4 Subnetting: Technical Guide Foundation calculations
1B IPv4 Subnetting: Instructor's Companion Trainer reference
1C IPv4 Subnetting: Teaching Companion Mentorship narrative
2 IP Addresses (Public vs. Private) Addressing fundamentals
3 NAT & Port Forwarding Traffic translation
4 DHCP Troubleshooting This document
5 DNS & Resolution Issues Name resolution
6 eero Mesh Network Architecture Product-specific topology
7 Quick Reference Cheat Sheet Rapid lookup
8 Troubleshooting Decision Trees Methodology assessment

Document Revision History

Version Date Author Changes
1.0 07/26/2026 [YOUR NAME] Initial version
1.1 07/26/2026 [YOUR NAME] Added APIPA troubleshooting flow
1.2 07/26/2026 [YOUR NAME] Incorporated pool capacity planning
1.3 07/26/2026 [YOUR NAME] Updated real ticket scenarios