How to factory reset D-Link DIR-878 rev A1 router – Default Login & Password

The D-Link DIR-878 rev A1 router has Gigabit WiFi, 4 Gigabit ETH-ports and 0 USB-ports. It has a total combined WiFi throughput of 2600 Mpbs.
It is also known as the D-Link AC1900 MU-MIMO Wi-Fi Gigabit Router.
How to factory reset D-Link DIR-878 rev A1 - Default Login & Password

D-Link DIR-878 rev A1 default Password , Login & Gateway settings :

If you have performed a reset of your DIR-878 rev A1 device or not changed the defaults, you
should
be able to access it with the following settings
Default Network name (SSID): dlink-XXXX
Default username: Admin
D-Link router default password list
Default subnet mask: 255.255.255.0

How to factory reset (hard reset) D-Link DIR-878 rev A1 :

You can factory reset your D-Link DIR-878 rev A1 in the following way(s)
With the reset button
Locate the reset button on the back off the router
While the unit is powered on, press the reset button with a sharp object (e.g. paperclip)
Hold the button pressed for 10 seconds, then release.
The unit will reboot by itself and once the WLAN light stops blinking the factory reset is done.
You can now setup your router again through the user interface

D-Link DIR-878 rev A1 router specifications :

System specs
CPU: 880 MHz
RAM: 128 MiB
Flash: 16 MiB
Custom firmwares: OpenWrt
Connectivity
WiFi: Gigabit (abgn+ac)
WiFi bands
2.4GHz & 5GHz
WiFi throughput: 2600 Mpbs
WAN
1 x Gigabit port
ETH
4 x Gigabit ports
USB-ports: 0