Low-power industrial cellular routers: a buyer’s guide for solar and battery-powered IoT deployments

One box. 4G connection, Wi-Fi, and power for four cameras. That is the Milesight UR35.

If you have ever installed a remote CCTV enclosure, you know the problem. You need a 4G router for cellular backhaul. You need a PoE switch to power the cameras. You need a Wi-Fi access point so engineers can connect on site without running cables. That is three devices to source, three power supplies, three sets of configuration, three points of failure.

The Milesight UR35-L0GEU-P-W puts all of that in a single IP30 metal enclosure the size of a fat paperback book. It is a 4G LTE Cat 4 dual SIM router, a four-port 802.3af/at PoE switch, and an 802.11b/g/n Wi-Fi access point in one unit. One 48 V power feed. One DIN rail clip. One management interface.

For anyone running 4G-connected CCTV installations, smart metering, industrial automation, BMS connectivity, vending, or transport — it is worth understanding what makes this router different and why Milesight building it matters.

Who is Milesight, and why does their background matter?

Milesight is a Chinese technology company founded in 2011 and now operating across two distinct divisions: IoT devices and AI cameras. That dual heritage is not incidental — it shapes every product they make.

On the camera side, Milesight builds AI-powered network cameras, NVRs, and video management software for surveillance applications. Their customer base expects cameras to keep recording when a network link drops. They expect footage to be protected. They expect systems to self-heal. Those are not nice-to-have features in video surveillance — they are requirements.

On the IoT side, Milesight produces LoRaWAN sensors, gateways, and cellular routers for smart buildings, utilities, smart metering, and industrial automation. These deployments are often in remote or unmanned locations. The router is the only thing standing between the sensor data and the cloud. If it fails, no one knows. So it cannot fail.

When Milesight engineers design a router like the UR35, they are not solving a home broadband problem. They are solving the connectivity requirements they encounter every day in their own camera and IoT deployments. That is why the UR35 has a hardware watchdog. That is why it has dual SIM. That is why it operates from -40 to +70 °C. They built the router they needed for their own kit.

If you want a compact Milesight router for lighter deployments, the Milesight UR41 is worth a look — credit-card sized, USB-C powered, with GPS and serial I/O. But for full industrial deployments where you need PoE, serial ports, and genuine multi-WAN resilience, the UR35 is the platform.

The 4G connection: dual SIM with genuine failover

The UR35-L0GEU-P-W uses a 4G LTE Cat 4 modem. Cat 4 gives you up to 150 Mbps download and 50 Mbps upload — fast enough for multiple HD camera streams, sensor telemetry, and a VPN tunnel running simultaneously without any of them suffering.

There are two Mini SIM (2FF) slots. You can put SIM cards from two different mobile network operators — EE and Vodafone, for example — and configure the router to fail over automatically if the primary SIM loses signal or the carrier has an outage. This is not a gimmick. On construction sites, in rural locations, and in road-side cabinets, single-operator coverage is not reliable enough for a system that needs to run 24 hours a day.

Failover works via ping detection. The router sends a test packet at a configured interval. If no reply comes back within the threshold, it switches SIMs. You set the parameters in the web GUI — which SIM is primary, how often to test, how many failures trigger a switch, and whether to revert to the primary SIM automatically once it recovers. None of this is automatic out of the box; you configure it once during commissioning, and then it runs.

Beyond dual SIM, the UR35 also supports Wi-Fi client mode as a third WAN path. So in an enclosure that also has a wired Ethernet feed, you can configure all three: Ethernet WAN as primary, SIM 1 as first failover, SIM 2 as second failover. The router manages the priority and the switching. For a deeper look at how 4G failover works in practice, see our guide to 4G failover and backup connectivity.

If your deployment needs 5G performance rather than Cat 4 LTE — high-throughput CCTV towers, dense sensor networks, or future-proofed infrastructure — the Semtech AirLink EX400 is worth considering. It runs 5G RedCap alongside LTE Cat 4, draws under 1 W at idle, and is built specifically for distributed IoT where full 5G power draw is not practical. Different product category, but relevant context if you are specifying for the long term.

The PoE capability: this is the part that changes how you specify remote enclosures

Let us spend some time on the PoE, because this is where the UR35-L0GEU-P-W genuinely earns its place.

PoE stands for Power over Ethernet. It is the technology that lets you send electrical power down the same Ethernet cable that carries data. A PoE power sourcing equipment (PSE) device — a switch or a router with PoE outputs — injects voltage onto the cable. A PoE-powered device (PD) — an IP camera, an access point, a sensor hub — extracts that power and uses it to run without its own mains or DC supply.

The UR35-L0GEU-P-W is a PoE PSE device. All four of its LAN ports output PoE power.

The standard it uses is IEEE 802.3af and 802.3at. These are the two most widely adopted active PoE standards. 802.3af delivers up to 15.4 W per port at the PSE. 802.3at — sometimes called PoE+ — delivers up to 30 W per port. The UR35 supports both, automatically negotiating with the connected device to supply the right amount. Most IP cameras, dome cameras, and PTZ cameras fall comfortably within 802.3at. The UR35 provides up to 30 W per port and up to 60 W total across all four LAN ports simultaneously.

This means you can connect up to four 802.3af/at IP cameras directly to the router’s LAN ports, and all four will receive power and network connectivity through a single Ethernet cable each. No separate PoE injectors. No separate switch. No additional power supplies for the cameras.

There is one hard requirement to understand: the UR35 must be powered by a 48 V DC supply for the PoE outputs to function. The router itself will run on 9-48 V DC, but the PoE PSE circuitry needs 48 V to operate. If you power the router at 12 V or 24 V, the router works but the PoE outputs are inactive. Plan your power supply accordingly during installation.

Also worth stating clearly: this is active PoE (802.3af/at), not passive PoE. Passive PoE systems — common in older IP camera installations and some access points — supply a fixed voltage (often 12 V or 24 V) without the handshake negotiation that active PoE uses. Do not connect a passive PoE device to the UR35’s LAN ports. The voltage levels are incompatible and you will damage the device. If you are in doubt about whether your cameras or access points are 802.3af/at compatible, check the datasheet or the label on the device before connecting.

Wi-Fi: the access point that replaces a separate unit

The -W suffix in the model name means this variant has an 802.11b/g/n (Wi-Fi 4) radio on 2.4 GHz. It runs as an access point or as a Wi-Fi client.

As an access point, it creates a local wireless network that engineers, maintenance laptops, handheld scanners, or tablets can connect to without needing a wired connection. For remote enclosures, this is useful during commissioning and on maintenance visits — you can connect a laptop without opening the cabinet and patching in. It supports WPA2 security with AES encryption, up to 15 simultaneous connections.

As a Wi-Fi client, it connects the router to an existing wireless network and uses that as a WAN path. Useful on sites that have existing broadband Wi-Fi coverage but no spare Ethernet port, or where you want to use the wireless network as a failover path.

One important note on the UR35 hardware architecture: Wi-Fi and GPS are mutually exclusive. The antenna connector on the front panel is either a Wi-Fi RP-SMA port (on -W variants) or a GPS SMA port (on -G variants). The UR35-L0GEU-P-W has Wi-Fi. If you need GNSS tracking alongside cellular connectivity, you would need the GPS variant instead.

The serial ports and I/O: connecting the things that are not on Ethernet

A lot of the equipment in remote industrial and utility installations does not speak IP. PLCs, RTUs, smart meters, energy monitors, alarm panels, and environmental sensors often communicate over RS232 or RS485 serial connections. The UR35 has both — one RS232 and one RS485 port on a 3.5 mm terminal block.

These are not just pass-through ports. The UR35 runs serial-to-IP gateway functions natively. Modbus RTU over serial becomes Modbus TCP over cellular. A smart meter speaking DLMS/COSEM over RS485 can send readings to a head-end system over MQTT or TCP across the 4G link. Transparent mode passes raw serial data as TCP or UDP to a remote server. All configured in the web GUI without additional middleware.

There is also a galvanically isolated digital input and a digital output. The DI can trigger an SMS alert, MQTT publish, email, or digital output change when its state changes. Useful for door open/close detection, pump status monitoring, alarm inputs, or generator run/stop sensing at remote sites. The DO is a wet-contact output rated at 0.3 A at 30 V DC — enough to trigger a relay or indicator.

If you need serial port connectivity without the full industrial chassis of the UR35, the Teltonika RUT906 is a compact alternative with RS232/RS485, dual SIM, and GPS in a smaller form factor. But it does not have PoE output — that remains unique to the UR35 in this category.

VPN and security: the industrial network is not the office network

Remote sites connected over cellular face a particular security challenge: standard SIM cards sit behind carrier-grade NAT. You cannot reach devices on the LAN side of the router by IP address from outside. That makes remote access to cameras, PLCs, or management interfaces difficult without additional infrastructure.

The UR35 supports a comprehensive VPN suite: WireGuard, OpenVPN (client and server simultaneously), IPsec (IKEv1 and IKEv2, multiple clients and server), GRE, L2TP, PPTP, DMVPN, and ZeroTier. In practice, for most remote access scenarios, WireGuard or OpenVPN to a VPN server with a public IP is the cleanest approach. Once the tunnel is up, the remote site LAN is reachable as if it were on the same local network.

The cleaner alternative — and the one we recommend for straightforward remote access — is a fixed IP SIM card. A fixed IP SIM gives the router a static, publicly routable IP address that does not change and is not behind carrier NAT. You can reach the router directly without a VPN server. The UR35 handles both approaches, and using a fixed IP SIM with a VPN tunnel gives you the best of both worlds: direct addressability and encrypted traffic.

Beyond VPN, the UR35 includes a full stateful packet inspection firewall with ACL, DMZ, port mapping, MAC binding, DoS and DDoS protection, and domain filtering. Authentication supports RADIUS, TACACS+, LDAP, and local accounts with multiple user authority levels. For deployments where a third-party contractor needs access to one device on the LAN but not the full network, this level of access control matters.

How does the UR35 compare to the Teltonika RUT200?

The Teltonika RUT200 is one of the most widely deployed compact 4G routers in the UK market and a product we know well. It is excellent at what it does: single SIM, compact, low power, solid RutOS software, and full Teltonika RMS remote management support. For a single-camera CCTV installation or a basic IoT monitoring application, it is hard to beat for simplicity and cost.

The UR35 is a different specification tier. Dual SIM rather than single. PoE output rather than none. RS232 plus RS485 rather than neither. Python SDK for on-device logic. A larger, heavier enclosure with DIN rail mounting as standard. If you are powering cameras, connecting serial equipment, or running multi-SIM failover from a single unit, the UR35 is the right choice. If you are deploying a simple 4G connection to a single device with no serial requirements and no cameras to power, the RUT200 is smaller, cheaper, and entirely adequate.

Management: one platform for everything in the field

The UR35 is managed via a web GUI at 192.168.1.1 by default. Configuration covers cellular settings, link failover priority, Wi-Fi, PoE port control, VPN, firewall, serial mode, and I/O — all in one interface. CLI access is available over SSH or Telnet.

For deployments with multiple units, Milesight’s DeviceHub platform handles centralised management, bulk configuration, firmware updates, and status monitoring across all deployed routers from a single dashboard. MilesightVPN provides encrypted remote access to devices on the router’s LAN side without requiring individual VPN configurations per site.

SNMP v1/v2c/v3 and TR-069 support means the UR35 fits into existing network management infrastructure without requiring a Milesight-specific platform. For more advanced deployments, the embedded Python SDK allows custom logic to run on the router itself — processing DI events, transforming serial data, or integrating with non-standard cloud platforms without additional hardware.

The enclosure: small enough for any cabinet, tough enough for any site

The UR35 measures 135 x 103 x 45 mm and weighs 485 g. The housing is metal, black, IP30 rated. It ships with a DIN rail clip for mounting inside a standard cabinet on a 35 mm DIN rail. A wall mounting bracket is available as an optional accessory.

The operating temperature range is -40 °C to +70 °C. Milesight notes that cellular performance may reduce above 60 °C — worth considering in south-facing cabinets in summer. Humidity tolerance runs from 0% to 95% non-condensing. The warranty is three years, which is longer than most competing products at this price point.

The specification in brief

Cellular: 4G LTE Cat 4, 150 Mbps down / 50 Mbps up, dual Mini SIM (2FF), automatic failover
PoE output: 4 x 802.3af/at PSE, up to 30 W per port, 60 W total (requires 48 V DC input)
Wi-Fi: 802.11b/g/n 2.4 GHz, AP or client mode, WPA2, up to 15 clients
Ethernet: 5 x Fast Ethernet (1 x WAN, 4 x LAN/PoE)
Serial: RS232 + RS485 with Modbus RTU/TCP gateway, DLMS/COSEM, MQTT
I/O: 1 x digital input, 1 x digital output, galvanically isolated
VPN: WireGuard, OpenVPN, IPsec, GRE, L2TP, PPTP, DMVPN, ZeroTier
Power input: 9-48 V DC (48 V required for PoE output)
Operating temperature: -40 to +70 °C
Dimensions: 135 x 103 x 45 mm
Warranty: 3 years

Where to buy

The Milesight UR35-L0GEU-P-W is stocked in the UK by The Router Store. You can buy the Milesight UR35-L0GEU-P-W here with next-working-day delivery if ordered before 3:00 PM. UK-based technical support is available if you need help specifying the right variant or planning your installation. If you need a fixed IP SIM card to go with it, those are stocked too.