Some firmware updates reset the router to factory defaults. You will need to re-enter your ISP username/password and your Wi-Fi network name (SSID) and password.
The D-Link DSL-124 is a wireless N300 ADSL2+ modem router, commonly found in home and small office environments relying on DSL (copper line) internet.
While the hardware is dated, the firmware is the most critical component. Unfortunately, the DSL-124 has a troubled security history. This article covers the known vulnerabilities, the final firmware versions, and why you should consider retiring this device.
The D-Link DSL-124 is end-of-life. No new firmware will be released. If your unit is functioning well on version 1.04, you can continue using it as a basic router. However, consider replacement if: D-link Dsl-124 Firmware
A modern replacement like the D-Link DSL-225 or a separate VDSL modem + router combo would be far more secure.
If the router does not come back online after 10 minutes:
Before updating, verify what you are running: Some firmware updates reset the router to factory defaults
If your version is lower than 1.04, and you are experiencing issues, an update is recommended.
This is the most critical step. Installing firmware intended for a different hardware version can permanently "brick" (render unusable) your router.
Always download firmware from official sources to avoid malware or corrupted files. The D-Link DSL-124 is a wireless N300 ADSL2+
Many enthusiasts ask: Can I run OpenWrt on the DSL-124?
Short answer: No. The DSL-124 uses a Broadcom BCM6328 chipset with proprietary ADSL drivers. OpenWrt has limited support for this family (the "brcm63xx" target), but the DSL-124 is not officially listed. Flashing a generic OpenWrt image will almost certainly brick the modem portion. The DSL-124 is not a good candidate for third-party firmware.
If you want advanced features, leave the DSL-124 as a pure modem (bridge mode) and connect a separate router running OpenWrt.