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Fixing Unifi Devices Reverting to Incorrect Inform Address

This guide addresses a persistent issue where Unifi devices (Access Points, Switches, etc.) show as "Offline" in the Unifi Controller and revert to an incorrect inform address even after using set-inform.

Problem Description

Unifi devices sporadically appear as "Offline" in the Unifi Controller. When checking the device status via SSH, the inform address is incorrect:

# Example output from 'info' command
Model:       UAP-AC-Lite
Version:     6.5.28.14491
MAC Address: <MAC>
IP Address:  <IP>
Hostname:    AP-Lite
Uptime:      584333 seconds
NTP:         Synchronized
Status:      Timeout (http://192.168.1.89:8080/inform)

The inform address (192.168.1.89 in this example) does not match the actual Unifi Controller address, causing the device to fail communication with the controller.

Common Solution (Often Unsuccessful)

The typical recommendation is to repeatedly run set-inform to overwrite backup configurations:

# SSH into the Unifi device
ssh ubnt@<device-ip>

# Run set-inform multiple times
set-inform http://<controller-ip>:8080/inform
set-inform http://<controller-ip>:8080/inform
set-inform http://<controller-ip>:8080/inform

Problem: This approach often fails because the device reverts to the incorrect address stored in its persistent configuration file.

Root Cause

The incorrect inform address is stored in the device's persistent configuration file at:

/etc/persistent/cfg/mgmt

This file contains management configuration that persists across reboots and takes precedence over set-inform commands.

Solution: Edit Persistent Configuration

Step 1: SSH into the Unifi Device

# SSH into the problematic device
ssh ubnt@<device-ip>

# Default credentials (if not changed):
# Username: ubnt
# Password: ubnt

Step 2: View Current Configuration

# View the management configuration file
cat /etc/persistent/cfg/mgmt

Example output:

mgmt.is_default=false
mgmt.led_enabled=true
mgmt.cfgversion=3d76e600b230b191
mgmt.authkey=
mgmt.selfrun_guest_mode=pass
mgmt.capability=notif,notif-assoc-stat
mgmt.use_aes_gcm=true
mgmt.report_crash=true
mgmt.is_setup_completed=false
mgmt.servers.1.url=http://192.168.1.89:8080/inform
stun_url=stun://<Unifi-Controller-IP>
mgmt_url=https://<Unifi-Controller-IP>:8443/manage/site/default

Step 3: Edit the Configuration File

Identify the incorrect inform address in the mgmt.servers.1.url line:

# Edit the file using vi (default editor on Unifi devices)
vi /etc/persistent/cfg/mgmt

Vi editor quick reference: - Press i to enter insert mode - Navigate to the mgmt.servers.1.url line - Change the incorrect IP address to your correct Unifi Controller IP - Press Esc to exit insert mode - Type :wq and press Enter to save and quit

Example change:

# Before
mgmt.servers.1.url=http://192.168.1.89:8080/inform

# After (replace with your actual controller IP)
mgmt.servers.1.url=http://192.168.1.100:8080/inform

Step 4: Reboot the Device

# Reboot the device to apply changes
reboot

Or trigger a provision from the Unifi Controller: 1. Go to Devices in the Unifi Controller 2. Select the device 3. Click Force Provision (gear icon → Advanced → Force Provision)

Step 5: Verify the Fix

After the device reboots, SSH back in and verify:

# Check device info
info

# Verify the inform address is correct
# Example output:
# Status:      Connected (http://192.168.1.100:8080/inform)

Alternative: Using sed for Quick Edit

If you're comfortable with command-line editing:

# Backup the original file
cp /etc/persistent/cfg/mgmt /etc/persistent/cfg/mgmt.backup

# Replace incorrect IP with correct IP (adjust IPs as needed)
sed -i 's/192.168.1.89/192.168.1.100/g' /etc/persistent/cfg/mgmt

# Verify the change
cat /etc/persistent/cfg/mgmt | grep mgmt.servers.1.url

# Reboot
reboot

Bulk Fix for Multiple Devices

If multiple devices have the same issue, create a script:

#!/bin/bash
# fix-unifi-inform.sh

CORRECT_CONTROLLER_IP="192.168.1.100"
INCORRECT_IP="192.168.1.89"

# List of device IPs
DEVICES=(
    "192.168.1.201"
    "192.168.1.202"
    "192.168.1.203"
)

for DEVICE in "${DEVICES[@]}"; do
    echo "Fixing device: $DEVICE"

    ssh ubnt@$DEVICE << EOF
        # Backup original file
        cp /etc/persistent/cfg/mgmt /etc/persistent/cfg/mgmt.backup

        # Replace incorrect IP
        sed -i 's/${INCORRECT_IP}/${CORRECT_CONTROLLER_IP}/g' /etc/persistent/cfg/mgmt

        # Verify change
        echo "New config:"
        cat /etc/persistent/cfg/mgmt | grep mgmt.servers.1.url

        # Reboot
        reboot
EOF

    echo "Device $DEVICE fixed and rebooting..."
    sleep 5
done

echo "All devices processed"

Make it executable and run:

chmod +x fix-unifi-inform.sh
./fix-unifi-inform.sh

Why This Works

The /etc/persistent/cfg/mgmt file is the device's persistent management configuration:

  1. Survives Reboots: Configuration persists across device restarts
  2. Takes Precedence: Overrides temporary set-inform commands
  3. Controls Failover: Defines backup inform addresses that devices fall back to
  4. Direct Configuration: Editing this file directly ensures the correct inform address is always used

Prevention

Set Correct Inform During Adoption

When adopting new devices:

  1. Ensure DNS resolves controller hostname correctly
  2. Use static IP or DHCP reservation for the Unifi Controller
  3. Configure devices with correct inform address from the start
  4. Use controller hostname instead of IP address when possible

Use Controller Hostname

Instead of IP addresses, configure using the controller hostname:

# Example with hostname
mgmt.servers.1.url=http://unifi.local:8080/inform

This prevents issues when the controller IP changes.

DHCP Option 43

For automatic controller discovery, configure DHCP Option 43:

# DHCP Option 43 format
01:<controller-ip-in-hex>

Example for controller at 192.168.1.100: 

01:C0A80164

Troubleshooting

Cannot SSH into Device

Solutions: - Verify SSH is enabled in controller settings - Check device IP address is correct - Try default credentials: ubnt / ubnt - Reset device to factory defaults if necessary - Connect via console cable if available

File is Read-Only

Solutions: - Ensure you're logged in as root or with sudo privileges - Remount filesystem as read-write: 

mount -o remount,rw /

Changes Don't Persist

Solutions: - Verify file was saved correctly: cat /etc/persistent/cfg/mgmt - Ensure the file path is exactly /etc/persistent/cfg/mgmt - Check for typos in the IP address - Reboot the device to apply changes - Re-provision device from controller

Device Still Shows Offline

Solutions: - Wait 5-10 minutes for device to reconnect - Check controller is reachable from device: ping <controller-ip> - Verify controller port 8080 is open: telnet <controller-ip> 8080 - Check firewall rules on controller and network - Force provision from controller interface - Review controller logs for adoption errors

Multiple Inform Addresses

If the file contains multiple mgmt.servers entries:

mgmt.servers.1.url=http://192.168.1.89:8080/inform
mgmt.servers.2.url=http://192.168.1.100:8080/inform

Update all entries to ensure consistency:

# Update all inform URLs
sed -i 's/mgmt.servers.[0-9].url=http:\/\/192.168.1.89/mgmt.servers.1.url=http:\/\/192.168.1.100/g' /etc/persistent/cfg/mgmt

Verification Checklist

After applying the fix:

  • [ ] Device shows as "Connected" in Unifi Controller
  • [ ] info command shows correct inform address
  • [ ] Device remains connected after reboot
  • [ ] Configuration changes sync from controller
  • [ ] Device statistics update in real-time

This solution applies to Unifi devices including UAP, USW, and USG models running UniFi firmware. Original solution credit: anakinfoxe.com