Search for the model number: https://openwrt.org/
Find your hardware in the supported devices lists:
Devices OpenWRT recommends: https://openwrt.org/toh/views/toh_available_864
Devices OpenWRT supports: https://openwrt.org/toh/start
Click “View/Edit data” to the right of your hardware
Click the link next to “Device Page:”
Follow the instructions on this page.
For the D-Link DIR-885L:
- Guide is here: https://openwrt.org/toh/d-link/d-link_dir-885l
- Download the firmware under “Firmware OpenWrt Install”
- Login to the router via the browser, the ip should be 192.168.0.1 or you can use the terminal to find it:
- Use the menu: Mangement > Upgrade
- Next to “Upgrade Firmware” click on “Select File” and choose the OpenWRT firmware.
- Wait while the router updates itself.
- Login to the router again using “ip r” to get the new gateway IP.