The UniFi Dream Machine SE is a rack gateway with a PoE switch built in, so a unit that restarts or runs very hot is usually suffering from a heavy PoE load, poor airflow or a power issue, and the controller's logs tell you more than the case does. Start with the environment. The UDM SE has fans and vents on the case, and in a closed cabinet or a tight rack space it recirculates hot air. Give it breathing room, and check that the fans spin and that dust is not packing the vents.
The checks in more detail
A device that is warm to the touch is normal; one that is too hot to hold, with the fans at full speed, is not. Look at the PoE load. The UDM SE has a PoE budget of 180 watts across its ports, and a set of access points and cameras that approaches or passes that limit makes the unit hot and may cause it to shed ports or restart. In the UniFi Network app, open the device's page and check the power use per port and the total. Move some devices to a separate PoE switch if you are near the limit.
A faulty PoE device that draws too much, such as a camera with a short, can also cause heat and instability, so unplug PoE devices one at a time to see whether the restarts stop. Check the power supply and the circuit. The UDM SE uses an internal supply with a mains cord, so test another outlet and, if you can, a protected power source such as a small UPS, which also protects it from dips. Look at the logs, in Settings, Control Plane, Console, for a reason for the restart, such as a firmware crash or a thermal event.
Update the firmware and the applications, since Ubiquiti fixes stability faults in updates. Heavy features, such as intrusion prevention at high speed with many rules, put a load on the processor and add heat, so check the IDS and IPS settings. A restart that comes at the same time each day may be a scheduled task or an update. If the unit still restarts with clear ventilation, a light PoE load, a good power source and current firmware, contact Ubiquiti support with the logs and the serial number.
Differential
Likely causes of “Ubiquiti UniFi Dream Machine Special Edition restarts, freezes or overheats”, and how to tell them apart
- 1
Poor airflow
What separates it Hot with fans at full speed
How to confirm Give it space and clean the vents
- 2
A PoE load near the 180 watt budget
What separates it Ports shed or the unit restarts
How to confirm Move devices to another PoE switch
- 3
A faulty PoE device
What separates it Heat and instability
How to confirm Unplug devices one at a time
- 4
A power source problem
What separates it Random restarts
How to confirm Try another outlet or a UPS
- 5
Heavy IDS or IPS load
What separates it High processor use
How to confirm Review the rules and firmware
Before you touch a setting
Record this first — changing settings destroys the evidence
- The PoE load
- The temperature and fan state
- The log reason for restarts
- The firmware version
Try in this order
0 of 6 completedCheck airflow
ReversibleSpace and clean vents.
Check the PoE load
ReversibleIn the UniFi Network app.
Unplug PoE devices one by one
ReversibleTo find a bad one.
Try another outlet or a UPS
ReversibleFor stable power.
Read the logs
ReversibleFor the restart reason.
Update the firmware
ReversibleAnd contact Ubiquiti.
Model-specific
What is true of this model and not of its siblings
- PoE budget
- 180 watts total.
- Rack
- Closed cabinets trap heat.
Stop boundary
When this stops being a self-service repair
- !If it restarts with good ventilation, a light PoE load and current firmware, contact Ubiquiti with the logs and serial number
- !Replace a faulty PoE device
- !Use a UPS
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why does my UDM SE restart?+
Heat, PoE load or power.
What is the PoE budget?+
180 watts across the ports.
Is warm normal?+
Yes, too hot to hold is not.
Does IPS add heat?+
Heavy rules add load.