4G Routers with PoE Out: A Practical Use Case Guide Leave a comment

What a 4G router with PoE out actually does

A 4G router with PoE out is two devices in one box. It is a cellular router that brings connectivity to a site with no fibre and no copper. It is also a Power Sourcing Equipment device that pushes power down the Ethernet cable to whatever you plug in. One camera, one cable. No injector, no local mains socket, no second enclosure.

That matters most at the sites where power is the hard part, not the network. Verge-mounted ANPR columns. Construction compounds. Substation kiosks. Pumping stations. In each case a separate injector means another item to specify, another item to fail, and another item to fit inside a cabinet that was never big enough. We stock five 4G routers with PoE PSE output, all from Milesight, and this guide covers what they do, how PoE works, and how to size the power correctly.

PSE and PD: which device does what

Power over Ethernet has two roles. Get them the wrong way round and nothing powers up.

PSE (Power Sourcing Equipment)

The PSE supplies the power. A PoE switch is a PSE. A PoE injector is a PSE. All five Milesight routers in this category are PSE devices: they put 48 V onto the LAN ports and feed the devices connected to them. They are not powered over Ethernet themselves.

PD (Powered Device)

The PD consumes the power. An IP camera is a PD. A wireless access point is a PD. A door reader, an IP intercom, a small edge gateway. The PD sits at the far end of the cable and takes what the PSE offers, after a negotiation the two of them run automatically.

How the negotiation works

Before any real voltage appears on the cable, the PSE checks for a 25 kΩ signature resistance in the PD. If it finds one, it classifies the device to work out how much power to reserve. Only then does it energise the port. This is why you cannot damage a non-PoE laptop by plugging it into a PSE port. No signature, no power. It is also why active PoE is safe to run into a general-purpose switch.

802.3af, 802.3at, and why passive PoE is a different thing

The Milesight routers support IEEE 802.3af and 802.3at. Both are active standards, meaning both run the detection and classification handshake described above.

• 802.3af (PoE): the PSE supplies up to 15.4 W per port. The PD receives up to 12.95 W once cable loss is accounted for.
• 802.3at (PoE+): the PSE supplies up to 30 W per port. The PD receives up to 25.5 W.
• 802.3bt (PoE++): not supported on these routers. If you need 60 W or 90 W for a heated PTZ dome or a high-draw AP, these are the wrong routers.

The classification the PSE performs maps a device to one of five classes. Class 1 reserves 4.0 W at the PSE, Class 2 reserves 7.0 W, Class 3 reserves 15.4 W, and Class 4 reserves 30 W. Class 0 is the fallback for a device that does not classify properly and reserves the full 15.4 W. This is worth knowing because a camera that draws 5 W in daylight may classify as Class 3 and reserve 15.4 W of your budget anyway.

Passive PoE is not the same thing. Passive PoE injectors dump a fixed voltage onto the cable with no handshake at all, usually 12 V or 24 V. Teltonika routers use passive PoE, as do many older camera systems. A passive PoE device will not power up from a Milesight PSE port, and a passive injector must never be connected to one. Check the label on your camera before you buy. If it says 802.3af or 802.3at, you are fine.

The 48 V rule

This is the single most important thing to understand about these routers, and it is where most first-time installs go wrong.

All five routers accept a wide DC input, 9 to 48 V. Feed one 12 V from a vehicle supply or 24 V from a control panel and it works perfectly as a 4G router. Cellular comes up, the LAN ports pass data, the VPN builds, everything behaves. But the PoE output stays off. The PSE circuitry needs a 48 V rail to generate compliant 802.3af/at output, and it cannot manufacture 48 V from a 24 V input.

The Milesight user guide states it plainly: 48 V DC is required for PoE output. So if you power the router at 12 V or 24 V and then wonder why the camera is dark, that is why. The Ethernet link light will be on. The camera will not be.

Every PoE variant we ship includes the 48 V PSU it needs, in the box, as standard. You do not buy it separately. The only time you need to think about this is when you are powering the router from something other than the supplied PSU: a DC bus, a solar controller, a vehicle, or a UPS. In those cases you must present 48 V at the terminal block or barrel connector, or the PoE ports will not energise.

Power budgets: what you can actually run

The per-port rating is not the whole story. Total power is shared, and the router takes its own cut first.

Start with the router. A UR35 draws typically 3.9 W and at most 4.6 W with the PoE circuit idle. That is the baseline before a single camera is connected. Then add the PSE conversion loss, which is real and typically costs you around 10% of what you deliver.

Now the devices. Typical draws, to be verified against the device label rather than assumed:

• Fixed dome or bullet IP camera: 4 to 8 W in daylight, rising to 8 to 12 W with IR illuminators active at night.
• PTZ camera with heater and wiper: 20 to 25 W, and usually Class 4. Budget for the heater, because it comes on when you are not watching.
• Wi-Fi access point: 10 to 13 W for older 802.11ac units, up to 25 W for a Wi-Fi 6 access point running both radios hot.
• IP intercom or door reader: 5 to 10 W typically.

A worked example on a four-port UR35. Three Class 3 cameras drawing 12.95 W each at the PD equals roughly 39 W delivered, which is around 46 W at the PSE once losses are counted, plus 4 W for the router. That comes to about 50 W and fits comfortably. Add a fourth Class 4 PTZ reserving 30 W and you are over the supply. Three cameras and one Class 2 door reader would fit. Four PTZ domes would not.

The correct approach is to add up the classification reservation of every device, not its average draw, then add the router, then compare that against the supply. Cameras draw their worst-case power at night, in winter, when nobody is on site to notice the port cycling.

Cabling: the boring part that breaks installs

Use solid-copper Cat5e or Cat6. Copper-clad aluminium is cheaper, has higher resistance, and drops enough voltage over a long run that a Class 3 camera can fail to power up at 70 m when it worked fine on the bench at 2 m. The 100 m Ethernet limit applies to PoE exactly as it applies to data.

Terminate both ends properly. PoE uses all four pairs on 802.3at, so a lazy two-pair termination that carries 100 Mbps data quite happily will halve your available current.

Real use cases, and the router that fits each one

Remote CCTV on an unserviced site

A construction compound, a fly-tipping hotspot, a plant yard. There is a camera and there is nothing else. No broadband, no cabinet, no mains near the pole. The Milesight UR32L-L0GEU-P is the cheapest way to solve this. Two Ethernet ports, both PoE PSE, 4G LTE Cat 4 backhaul, and a normal operating draw of 1.8 W before the camera is attached. Note it uses a single cellular antenna, so there is no MIMO gain to chase. Fit a decent external antenna and get the signal right instead.

A camera plus site Wi-Fi from one enclosure

Welfare cabins, event compounds, temporary traffic management. You need a camera powered and you also need staff to get onto Wi-Fi. The Milesight UR32S-L0GEU-P adds a 2.4 GHz radio to the same two-port PoE platform, so the router is the access point and one PoE port still feeds the camera. It also does automatic failover between a wired WAN and cellular, which matters when the site gets a temporary broadband line halfway through the project and you want it used as primary.

Utility telemetry with a camera on the same box

Water and wastewater sites, pressure-reducing valve chambers, remote substation kiosks. There is a Modbus RTU device on RS485 that has to reach a SCADA head end, and there is also a camera on the door. The Milesight UR32-L0GEU-P-W-485 handles both. RS485 with a Modbus RTU to Modbus TCP gateway, isolated digital input and output for a door contact or an alarm relay, PoE on both LAN ports, and dual SIM so a single carrier outage does not take the site off the map.

Multi-camera compounds and ANPR

Car parks, weighbridges, depot entrances. Four cameras, one entry ANPR unit, no infrastructure. The Milesight UR35-L0GEU-P gives you four PoE PSE ports on LAN1 to LAN4, dual SIM failover, RS232 and RS485, and a microSD slot for local buffering when the cellular link drops. Fit SIMs from two different networks and the site keeps reporting through a single-carrier outage. See our 4G CCTV range for camera and SIM bundles.

Access control, door entry, and a Wi-Fi bridge

Gated yards and agricultural sites where you need a door reader powered, an intercom powered, and Wi-Fi coverage across a barn or a workshop. The Milesight UR35-L0GEU-P-W is the UR35 with an 802.11b/g/n radio added. Four PoE ports, dual SIM, serial, digital I/O, and a Python SDK if you want to run logic locally rather than round-tripping every decision to a cloud platform.

EV charge point management

Where an OCPP charge point sits alongside a camera watching the bay, the UR35 variants earn their keep. One 48 V feed into the cabinet powers the router and the camera, and the router carries OCPP traffic to the back office over cellular while the camera streams over the same link.

Choosing between the five

Start with port count. Two PoE devices or fewer means a UR32, and the UR32 series is the smaller enclosure. Three or four PoE devices means a UR35.

Then check for serial and dual SIM. The UR32L and UR32S are single SIM with no serial port. The UR32-L0GEU-P-W-485 and both UR35 variants have dual SIM. The UR35 pair adds RS232 alongside RS485 and takes a 2×2 MIMO cellular antenna, which the Lite series does not.

Then decide on Wi-Fi. The UR32L and the UR35-L0GEU-P have none. The UR32S, the UR32-P-W-485, and the UR35-P-W do.

Frequently asked questions

Can I run these routers on 12 V or 24 V?

Yes, as routers. All five accept 9 to 48 V DC input and will route, build VPN tunnels, and pass Ethernet data normally. The PoE PSE output will not work below 48 V. If you are powering PoE devices, use the supplied 48 V PSU or present 48 V from your own supply.

Are these routers themselves powered over Ethernet?

No. They are PSE devices, not PD devices. They source power out; they do not draw it in over Ethernet. If you need a router that is itself PoE powered, that is a different product.

Will my existing passive PoE camera work?

No. Passive PoE at 12 V or 24 V is not compatible with 802.3af/at active PoE. The router will not detect a signature resistance and will not energise the port. Check the camera label or datasheet for an 802.3af or 802.3at marking.

How many cameras can one router power?

It depends on their PoE class rather than their port count. Add up the class reservation of every device, add the router’s own draw, and compare that against the supply. Three or four Class 2 or Class 3 cameras is a normal UR35 load. Four Class 4 PTZ domes is not.

Do I need a fixed IP SIM?

If you need to reach the camera or the router from outside, yes. Standard SIMs sit behind carrier-grade NAT, so inbound connections do not reach the device. A fixed IP SIM removes that constraint. The alternative is an outbound VPN tunnel from the router to your own endpoint, which all five models support.

Can I manage a fleet of these remotely?

Yes. All five support the Milesight Development Platform for remote status, alerting, configuration, and firmware rollout across multiple sites from one dashboard.

Related products and further reading

Browse the full 4G routers with PoE PSE category, or the wider Milesight 4G router range. For camera sites, pair the router with a 4G antenna sized for your signal conditions and an IoT SIM card or fixed IP SIM. If you need to power more devices than the router has ports, add a PoE switch downstream. All routers are held in UK stock with next-working-day delivery, backed by UK-based technical support. Call us on 0300 124 6181 if you want a hand sizing the power budget before you order.