Edge Router vs. Firewall: Understanding Key Security Roles at the Edge

The edge router vs firewall debate is a common point of confusion. Let's simplify it: A firewall is a function (a security guard that inspects traffic). An edge router is a device (a border checkpoint) that must perform that function. This guide explains how every modern edge router is a stateful firewall, why this edge router security is critical, and how it differs from a specialized "Next-Generation Firewall" (NGFW).

If you're designing a secure network for your factory or branch office, you've hit the big question: "Do I need an edge router and a firewall, or does the edge router do the firewalling?"

I've seen millions spent on redundant or incorrect hardware because of this simple confusion. Let me be clear: A firewall is a function. An edge router is a device. And in 2025, any edge router worth its salt is a powerful firewall.

The line has completely blurred, and that's a good thing. It means a single, hardened device can (and should) be your secure border checkpoint. Let's break down the roles.

A firewall is a "security guard" for your network. Its job is to stand at a checkpoint and inspect every "data packet" (a piece of information) that tries to pass, in or out. It checks the packet against a set of rules (an Access Control List, or ACL) and decides to either Allow or Deny it.

But not all firewalls are created equal.

This is the old, basic version. It only looks at the packet's "envelope" (the Layer 3/4 header).

• Rule: "Only allow packets from IP address 1.2.3.4."
• Problem: It's dumb. It doesn't know if a packet is a legitimate response to a request your computer made, or a new, malicious attack from that IP address.

This is the modern standard and the minimum you should accept. A stateful firewall is a "guard with a memory."

• How it works: When your computer (192.168.1.50) sends a request out to a web server, the firewall notes it in its "state table." When the server's response comes back to 192.168.1.50, the firewall checks its table and says, "Ah, this is a response to a conversation we started. I'll allow it."
• Security: If a hacker tries to send an unsolicited packet from that same server, the firewall checks its table, finds no matching conversation, and Denies the packet.
• This is the key: A stateful firewall is the foundation of modern edge router security.

As we covered in our Ultimate Guide, an edge router is the "border checkpoint" device. Its job is to connect your trusted internal LAN to the untrusted external WAN (the internet).

Because your edge router is at the border, it must be the security guard.

In the 1990s, you might have had a router and a separate firewall. Today, those functions have merged. A modern industrial edge router is a high-performance device whose primary jobs are:

1. Routing: Directing traffic between LAN and WAN.
2. Firewalling: Acting as a stateful firewall to protect the LAN.
3. Secure Connectivity: Acting as a VPN endpoint to encrypt all WAN traffic.

You don't buy an edge router and a firewall. You buy an edge router that is a powerful firewall.

For 99% of all industrial, retail, and branch office deployments, your edge router is your primary firewall. This is the most secure and efficient architecture.

When you deploy a Robustel edge router, like the R5020 Lite (a 5G edge router) or the Add One Product: EG5120 (an edge computing gateway), you are deploying a powerful security appliance.

• Stateful Firewall: Its RobustOS software includes a sophisticated stateful firewall.
• VPN Hub: It's a high-performance VPN endpoint, ready to build secure IPsec or OpenVPN tunnels.
• OT/IT Segmentation: You can configure its firewall rules to create a "DMZ" that isolates your critical OT network (PLCs, sensors) from your IT network (PCs, printers), all within one edge router.

This single, hardened edge router is the only device you need at your network edge to provide both secure connectivity and robust firewalling.

This is the final point of confusion. You'll hear vendors like Palo Alto or Fortinet talk about "Next-Generation Firewalls." So is that different from an edge router?

A key insight: An NGFW is just a hyper-specialized edge router.

It does everything a normal edge router does (routing, stateful firewall, VPN), but adds one, processor-intensive feature:

• Layer 7 Inspection: It "opens the envelope" and reads the mail. It inspects the actual data inside the packet. It can identify applications (e.g., "This is Facebook traffic," "This is a SQL database query," "This looks like the WannaCry ransomware signature").
• Use Case: Primarily for corporate IT. It's designed to stop employees from using file-sharing apps or to find malware hidden inside a web download.

For 90% of industrial OT security, an NGFW is expensive overkill. Your PLC isn't browsing Facebook.

• Your industrial edge router needs to be a powerful Layer 3/4 stateful firewall. Its job is to make your OT network invisible.
• Rule 1: Block ALL incoming traffic.
• Rule 2: Only allow an established VPN tunnel from HQ.
• Rule 3: Only allow outbound MQTT data to a specific cloud IP.

A Robustel edge router is built to do this job perfectly. You don't need a $5,000 NGFW to perform these essential, high-security tasks.

To end the edge router vs firewall confusion, stop thinking of them as two different devices. A firewall is a feature that your edge router must have.

You don't need to buy "an edge router AND a firewall." You need to buy one edge router that has the right kind of firewall for your job.

• For Corporate IT (Protecting Users): You may need an NGFW (a Layer 7 edge router) to inspect user web traffic.
• For Industrial OT (Protecting Machines): You need a rugged industrial edge router (like a Robustel) with a powerful Stateful Firewall (Layer 3/4) and robust VPN capabilities.

A professional industrial edge router is your security solution. And with a platform you can manage the firewall rules and VPN certificates for your entire edge router fleet from one place, ensuring your security is always consistent and up-to-date.