WL-520g

The ASUS WL-520g router has 54mbps WiFi, 4 100mbps ETH-ports and 0 USB-ports. It also supports custom firmwares like: dd-wrt, OpenWrt

Quick links:
Default password/Login
Login instructions
User Manuals
Flashing Custom Firmwares

WL-520g router specifications (specs)

System specs
CPU: n/a
RAM: 8 MiB
Flash: 2 MiB
Custom firmwares: dd-wrt, OpenWrt

Connectivity
WiFi: 54mbps (bg)
WiFi bands: 2.4GHz
WiFi throughput: n/a
WAN: 1 x 100mbps port
ETH: 4 x 100mbps ports
USB-ports: 0

Hard reset instructions for ASUS WL-520g

If your WL-520g router is not working as it should, dropping connections or not being responsive, you should first do a reset of the router to see if the problems persist. Other scenarios where you might want to reset your router is if you've forgotten the password or misconfigured it and can't get access anymore.
Your can reset your ASUS WL-520g in the following way(s):

Through the web-interface

Open your browser and navigate to the default gateway ip (check default settings below)
Sign in to the web-interface with the username and password you have selected, or try the defaulr username and password (check default settings below)
Under the advanced settings menu, select administration
Find the link "Restore/Save/Upload Setting"
Beside Factory default click on Restore
If prompted, click ok

With the reset button on the router

Locate the reset button on the backside of your unit
with a sharp object, e.g. a paperclip or pencil, press and hold the reset button for 5s or until the power led starts flashing

The 30-30-30 reset

If the above instructions don't work you can always try the 30-30-30 reset as follows:

When router is powered on, press the reset button and hold for 30 seconds. (Use a paper clip or something sharp)
While holding the reset button pressed, unplug the power of the router and hold the reset button for 30 seconds
While still holding the reset button down, turn on the power to the unit again and hold for another 30 seconds.

This process usually works for resetting any router to it's factory setting.

Note: It is worth reading more about how to reset routers with the 30 30 30 reset and what the risks and considerations are when resetting your router this way, instead of just rebooting it.

Default factory settings for ASUS WL-520g

If you have performed a reset of your WL-520g device or not changed the defaults, you should be able to access it with the following settings:

Default Gateway IP: 192.168.1.1 ASUS login instructions
Default username: admin ASUS router default password list
Default password: admin
Default subnet mask: 255.255.255.0
Default DNS server: 192.168.1.1
Note: If you are using the default settings you should change them to increase security and prevent unathorized access to your network.

To login to the WL-520g router and change the settings, you can follow these steps:

Make sure you are connected to the router's network, either by Wi-Fi or ethernet cable.
Open your browser and visit http://192.168.1.1
You should be prompted with a login dialogue.
Enter the username: admin and the password admin
Note: If you have already changed the password use that instead.
You will now be logged in. If you haven't yet changed the defaul password, we recommend that you change it first thing you do after logging in.

If these instructions don't work for your router, you can always try a factory reset to get the default, or try some other common ASUS credentials, as they can usually be shared across models/variants.

WL-520g Firmwares

Staying up to date with the latest firmware is a good idea to keep your router even more secure from various security flaws.
If you want to squeeze a little bit of extra functionality out of your router, consider flashing an open-source firmware like dd-wrt, openWRT or LEDE. Flashing a custom ROM can greatly increase the stability and functionality of your old router.
Following are the firmwares that we have identified existing for the ASUS WL-520g:

Flashing dd-wrt on the ASUS WL-520g

Since the WL-520g has 2 MiB of flash memory, you should choose a stripped down version of dd-wrt that fits on the smaller flash. We haven't find any specific instructions for flashin dd-wrt onto the ASUS WL-520g, but you can read the Installation guide over at dd-wrt to get a clue on how to proceed (As this model is listed as supported).
Note: Always make sure to read the wiki and howtos of dd-wrt before doing any flashing.

Flashing OpenWrt on the ASUS WL-520g

The ASUS WL-520g is supported by OpenWrt according to their Table of Hardware. So flashing OpenWrt onto it should be quite straigthforward.
We couldn't find any specific instructions for flashin OpenWrt on the ASUS WL-520g, but since it's listed in their Table of Hardware as supported, you can head over to the OpenWrt install instructions and read on there.
Note: Flashing custom firmwares is always on you're on own risk. Make sure to read OpenWrt's wikis to understand the risks and how to proceed if something goes wrong.