WZR-900DHP

The Buffalo WZR-900DHP router has 300mbps WiFi, 4 N/A ETH-ports and 0 USB-ports. It also supports custom firmwares like: dd-wrt

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

WZR-900DHP router specifications (specs)

System specs
CPU: 800 MHz
RAM: 256 MiB
Flash: 128 MiB
Custom firmwares: dd-wrt

Connectivity
WiFi: 300mbps (abgn)
WiFi bands: 2.4GHz & 5GHz
WiFi throughput: n/a
WAN: 1 x N/A port
ETH: 4 x N/A ports
USB-ports: 0

Hard reset instructions for Buffalo WZR-900DHP

If your WZR-900DHP 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 Buffalo WZR-900DHP in the following way(s):

The 30-30-30 reset

There are no specific instructions for this model yet, but you can always do 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. If that doesn't work be sure to check out the questions and answers incase someone else has had similar problems resetting their router.

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 Buffalo WZR-900DHP

If you have performed a reset of your WZR-900DHP device or not changed the defaults, you should be able to access it with the following settings:

Default subnet mask: 255.255.255.0

Note: If you are using the default settings you should change them to increase security and prevent unathorized access to your network.

WZR-900DHP 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 Buffalo WZR-900DHP:

Flashing dd-wrt on the Buffalo WZR-900DHP

Since the WZR-900DHP has 128 MiB of flash memory, you should be able to run dd-wrt with full functionality without having to worry too much about which firmware to use. We haven't find any specific instructions for flashin dd-wrt onto the Buffalo WZR-900DHP, 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.