POS Network & Connectivity

Typical POS Network Architecture

A POS installation is a small local network connecting all the hardware that processes transactions:

Internet / WAN
      ß”‚
   Router / Firewall
      ß”‚
   Network Switch (managed preferred)
      ß”?ß”€ß”€ POS Terminal 1 (Ethernet)
      ß”?ß”€ß”€ POS Terminal 2 (Ethernet)
      ß”?ß”€ß”€ Receipt Printer (Ethernet)
      ß”?ß”€ß”€ Card Payment Terminal (Ethernet)
      ß””ß”€ß”€ Back-office PC / Server

Wireless (Wi-Fi) is used only for mobile/tablet POS or handheld scanners. Fixed POS terminals should always use Ethernet for reliability.

IP Address Management

Static IP vs DHCP

Approach	Use for
Static IP	Receipt printers, card terminals, networked scanners ߀” POS software must know their address
DHCP reservation	Assign a fixed IP from the router by MAC address ߀” easier to manage than manual static IPs
DHCP dynamic	Only for POS terminals themselves if the POS software connects outbound

Printers and card terminals need a fixed IP because the POS software is configured with that address. If the IP changes, the printer or terminal becomes unreachable.

Configuring a Networked Receipt Printer

Most Epson/Star/Citizen/BIXOLON Ethernet printers use a web configuration page:

1. Print a self-test page to find the current IP (hold the feed button while powering on)
2. Open that IP in a browser ߀” the printer's web interface appears
3. Navigate to TCP/IP settings
4. Assign a static IP within the same subnet as the POS terminals (e.g. 192.168.1.50)
5. Set the subnet mask and default gateway to match the network
6. Save and reboot the printer
7. Update the IP in the POS software configuration

VLANs and Network Segmentation

In larger or security-conscious installations, POS devices are placed on a separate VLAN:

• PCI DSS requirement: cardholder data environment (CDE) must be isolated from general business networks
• Card terminals should be on a dedicated VLAN with no access to office PCs or Wi-Fi guest networks
• The router/firewall enforces which VLANs can communicate

A simple rule: card terminals talk only to the payment processor's cloud endpoint ߀” nothing else.

Card Terminal Network Requirements

Requirement	Details
Outbound HTTPS (port 443)	To payment processor / acquirer ߀” must not be blocked
DNS resolution	Terminal must resolve hostnames; set a reliable DNS server
Low latency	High latency causes transaction timeouts; keep POS on wired connection
No HTTP proxy	Most terminals do not support proxy authentication
Static or reserved IP	Some acquirer integrations require a known terminal IP

If transactions are timing out, check: firewall rules, DNS settings, and cable/switch health.

Wi-Fi Considerations for Mobile POS

• Use 5 GHz band for tablets/mobile terminals ߀” less interference than 2.4 GHz
• Ensure adequate access point coverage ߀” dead zones cause mid-transaction disconnects
• Use WPA2-Enterprise or WPA3 ߀” avoid open networks
• Isolate POS Wi-Fi SSID on a dedicated VLAN separate from customer Wi-Fi

Remote Access for Support

POS systems often need remote management by a vendor or IT support:

Method	Notes
TeamViewer / AnyDesk	Common for Windows-based POS; requires internet access
VPN + RDP	More secure; IT connects via VPN then RDP to the POS terminal
Static public IP	Required if the support vendor connects directly; get from ISP
Dynamic DNS (DDNS)	Maps a hostname to a changing public IP ߀” useful if static IP is unavailable

Always ensure remote access software is only active when needed, and uses strong authentication.