Router firmware is the small operating system burned into the box in your hallway, and the reason to care is unglamorous: vendors ship security patches in these files months before they mention anything publicly. A router bought in 2021 running its launch firmware has missed four or five rounds of fixes.
Match the hardware revision, not the model name
Turn the router over and read the label. It will say something like Model: Archer C6 / Ver: 3.20. That version number matters because manufacturers publish separate firmware files for each hardware revision, and a v1 file on a v3 board usually produces a brick rather than a warning. Enter the model and revision on the vendor’s support page, download the file (typically 10–30 MB, ending in .bin or .trx), and check the published checksum if one is listed.
Note the admin address while you are at it: tplinkwifi.net or 192.168.1.1 for TP-Link, routerlogin.net for Netgear, asusrouter.com for Asus, 192.168.8.1 for most Huawei units. The default username and password are printed on the same sticker — if they are still in use, that is the first thing to change after the update.
Write down what the router currently knows
Open Administration → Backup / Restore (or the equivalent) and save the configuration file to a laptop, not to a phone. Then, on paper or in a notes app, record the WAN connection type: DHCP, PPPoE, or a static address with gateway and DNS. PPPoE is the one that bites — the ISP username and password often appear only on the installation slip, and a factory reset during a firmware jump wipes them. Call the ISP and get them before you start, not after.
Also capture the Wi-Fi name and passphrase for both bands, any DHCP reservations, port forwards, and the IPTV VLAN ID if your connection carries television. None of this takes more than ten minutes, and all of it is unrecoverable once the flash completes.
Flash over cable with the power protected
Connect the laptop to a LAN port with an Ethernet cable and turn the laptop’s Wi-Fi off, so the browser session cannot drop mid-upload. Do not attempt this over a wireless link — a stall at 60% is the classic way to kill a router.
Plug the router into a UPS if you have one. In areas with load-shedding, a two-minute outage during the write is the single most common cause of a dead unit, and no recovery procedure is guaranteed. The update itself takes two to five minutes; leave the browser alone, resist the urge to refresh, and ignore any “not responding” message.
Where the upgrade screen offers “restore factory defaults after upgrade”, accept it. Old configuration files regularly fail to load on a new major version, and a router that boots with half-applied settings is harder to debug than one that boots clean.
Verify the result, then re-secure it
After the reboot, the status page should show the new version string exactly matching the file you downloaded. Check that the WAN address is a real value rather than 0.0.0.0 — if it is blank, the PPPoE credentials or DHCP setting did not survive. Then confirm the Wi-Fi name and passphrase, re-add any port forwards, and run a speed test from a wired client.
While you are in there: set encryption to WPA2-PSK (AES) or WPA3 if every device supports it, disable WPS and remote management, and change the admin password. Put 2.4 GHz on channel 1, 6 or 11 and leave 5 GHz on auto unless you live in a dense building, where 36–48 or 149–165 usually behave better. Asus documents this whole web-interface procedure in its official firmware update guide, and the steps are near-identical across brands.
If the update goes wrong
A router with a blinking power LED and no web interface is usually recoverable, not dead. Hold the reset pin for ten seconds, then use the vendor’s recovery mode — TP-Link and several others expect a static IP of 192.168.0.2 on the laptop and a TFTP upload to 192.168.0.1. Keep the previous firmware file on the laptop for a week after upgrading, and do not delete it until the new version has run without dropouts.
Two related jobs are worth doing in the same sitting: re-checking where the router sits, since a firmware update is a good excuse to move it off the floor, and re-testing the guest network, which is often reset to default after a major version change.