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Internet Network Communications

Configuring an old Linksys device as a wifi access point

Adam

• 5 min read
Configuring an old Linksys device as a wifi access point

I'm pausing for a moment on setting up our VPN on E3000 and I want you to help me install Open WRT on another old Cisco router I have Linksys E2500 FCC ID Q87-E2500
This E2500 will be used only as a wireless access point, piggy backing via ethernet cable plugged into E3000
So obviously, I need to disable DHCP and any other service that are not needed to only function as a wifi access point

Grok-4 said:
Step 1: Verify Compatibility and Download Firmware
Before proceeding, note that the Linksys E2500 v1 (based on your FCC ID Q87-E2500) is supported by OpenWRT, but it uses a Broadcom WiFi chipset (BCM43236), which has limited support in OpenWRT. This means WiFi functionality may work partially (e.g., 5GHz in AP mode, limited 2.4GHz features like channel scanning), but it could have issues with stability, full speed, or certain modes. Ethernet works fine, but since you're using this as a WiFi access point, test WiFi thoroughly after installation. If WiFi doesn't meet your needs, consider a different router or sticking with stock firmware.

  1. Reset the E2500 to factory defaults if it's not already (to ensure a clean start):
    • Power on the router.
    • Use a paperclip to press and hold the reset button on the back for 10-15 seconds until the lights flash.
    • Release and wait for it to reboot.
  2. Connect your computer to the E2500 via Ethernet (use one of the LAN ports, not WAN).
  3. Access the stock Linksys web interface at http://192.168.1.1 (username: leave blank or "admin"; password: "admin").
  4. Download the latest stable OpenWRT firmware for the E2500 v1:
    • Go to https://downloads.openwrt.org/releases/ (check for the newest release; as of now, it's around 24.10.0 or later).
    • Navigate to targets/bcm47xx/mips74k/.
    • Download the file named openwrt-[version]-bcm47xx-mips74k-linksys_e2500-v1-squashfs.bin (this is the factory image for initial installation from stock firmware).

Step 2: Install OpenWRT

  1. In the stock Linksys web interface, go to Administration > Firmware Upgrade.
  2. Click Browse or Choose File, select the downloaded .bin file.
  3. Click Start Upgrade or Upgrade and confirm if prompted.
  4. Wait patiently (5-10 minutes) for the process to complete and the router to reboot. Do not interrupt power.
  5. After reboot, the router should now run OpenWRT. Access it at http://192.168.1.1 (no username/password by default; set one later for security).

If the upgrade fails or the router doesn't boot properly:

  • Try a 30-30-30 reset: Hold reset for 30 seconds while powered on, unplug while holding for 30 seconds, plug back in while holding for another 30 seconds.
  • If bricked, use TFTP recovery (detailed on the OpenWRT wiki if needed, but this is rare for this model).

Step 3: Initial Setup and Access

  1. Connect your computer to a LAN port on the E2500.
  2. Open a web browser and go to http://192.168.1.1 to access LuCI (OpenWRT's web interface). If it prompts, set a password for the root user.
  3. Alternatively, for SSH access:
    • SSH to 192.168.1.1 as root (no password initially).
    • Set a password immediately: Run passwd and follow prompts.

Update packages if needed: In SSH, run opkg update (requires internet; connect the E2500's WAN port temporarily to your E3000 or another internet source).

Step 4: Configure as a Wireless Access Point (Dumb AP Mode)

The goal is to connect the E2500 via Ethernet to the E3000 (LAN-to-LAN), disable routing/DHCP, and have it only provide WiFi on the same network as the E3000. Assume your E3000's LAN subnet is 192.168.1.0/24 (default; adjust if different) and its IP is 192.168.1.1.

  1. Log into LuCI at http://192.168.1.1.
  2. Go to System > Administration and set a strong root password if not done.
  3. Go to Network > Interfaces:
    • Edit the LAN interface:
      • Set Protocol to Static address.
      • Set IPv4 address to something unused in your E3000's subnet, e.g., 192.168.1.2.
      • Set IPv4 netmask to 255.255.255.0.
      • Set IPv4 gateway to your E3000's IP (e.g., 192.168.1.1).
      • Set DNS servers to your E3000's IP or a public one like 8.8.8.8.
      • Save & Apply.
    • Delete or disable the WAN and WAN6 interfaces (not needed for AP mode).
  4. Go to Network > DHCP:
    • Uncheck Enable DHCP for the LAN interface.
    • Save & Apply.
  5. Go to Network > Firewall:
    • Disable the firewall (set to "disabled" or delete rules) since the E3000 handles this.
    • Save & Apply.
  6. Go to Network > Wireless:
    • Enable the WiFi radios (there may be 2.4GHz and 5GHz; test both due to limited support).
    • For each radio:
      • Set Mode to Access Point.
      • Set SSID to match your E3000's WiFi (for seamless roaming) or a new one.
      • Set Network to lan (bridges WiFi to the LAN interface).
      • Set security (WPA2-PSK or better) to match your E3000 if using the same SSID.
    • Save & Apply.
  7. Reboot the router via System > Reboot.

Via SSH (Command Line, for Precision):

  1. SSH to 192.168.1.1 as root.
  2. Edit the network config: vi /etc/config/network
    • Under config interface 'lan':
      • Set option proto 'static'
      • Set option ipaddr '192.168.1.2' (or your chosen static IP)
      • Set option netmask '255.255.255.0'
      • Set option gateway '192.168.1.1'
      • Add option dns '192.168.1.1 8.8.8.8' (adjust as needed)
    • Remove sections for wan and wan6.
    • Save and exit (:wq).
  3. Disable DHCP: vi /etc/config/dhcp
    • Under config dhcp 'lan':
      • Set option ignore '1'
    • Save and exit.
  4. Disable firewall: /etc/init.d/firewall stop; /etc/init.d/firewall disable
  5. Configure WiFi: vi /etc/config/wireless
    • For each config wifi-iface section:
      • Set option mode 'ap'
      • Set option ssid 'YourSSID'
      • Set option encryption 'psk2' (or match your security)
      • Set option key 'YourPassword'
      • Set option network 'lan'
    • Enable radios: Remove option disabled '1' if present.
    • Save and exit.
  6. Apply changes: wifi reload; /etc/init.d/network restart
  7. Reboot: reboot

Step 5: Physical Setup and Testing

  1. Power off both routers.
  2. Connect an Ethernet cable from a LAN port on the E3000 to a LAN port on the E2500 (do not use the WAN port on the E2500).
  3. Power on the E3000 first, then the E2500.
  4. Test:
    • From a device connected to the E2500's WiFi, check if you get an IP from the E3000's DHCP (e.g., 192.168.1.x).
    • Ping the E3000 (192.168.1.1) and external sites.
    • Access the E2500's LuCI/SSH at its new static IP (e.g., 192.168.1.2).
    • Verify WiFi speed/stability; if issues arise due to Broadcom limitations, consider using only Ethernet or a different channel.

If WiFi doesn't work as expected, you can revert to stock firmware via LuCI (System > Backup/Flash Firmware > Upload stock .bin from Linksys support site) or TFTP.

This setup keeps the E2500 minimal: no DHCP, no routing, just WiFi extension. Let me know if you encounter issues or need tweaks!