TL-WR850N v1

The TP-LINK TL-WR850N v1 router has 300mbps WiFi, 4 100mbps ETH-ports and 0 USB-ports.

Quick links:
Default password/Login
Login instructions

TL-WR850N v1 router specifications (specs)

System specs
CPU: 580 MHz
RAM: 64 MiB
Flash: 8 MiB
Custom firmwares: OpenWrt

Connectivity
WiFi: 300mbps (bgn)
WiFi bands: n/a
WiFi throughput: n/a
WAN: 1 x 100mbps port
ETH: 4 x 100mbps ports
USB-ports: 0

Hard reset instructions for TP-LINK TL-WR850N v1

If your TL-WR850N v1 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 TP-LINK TL-WR850N v1 in the following way(s):

Through the web interface

Open a browser and navigate to the web interface of the router (check default settings below)
In the menu look for System tools and under there find the Factory defaults option
On the Factory defaults page click on the Restore button to perform the reset.

Withe the RESET/WPS button

Have the unit powered on
Press and hold the reset (sometimes reset/WPS) button for 10 seconds with a paperclip or other sharp object.
When the SYS led start blinking quickly release the reset button and wait for router to boot back up.

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 TP-LINK TL-WR850N v1

If you have performed a reset of your TL-WR850N v1 device or not changed the defaults, you should be able to access it with the following settings:

Default Network name (SSID): TP-LINK_XYXYXYX
Default Gateway IP: 192.168.0.1 TP-LINK login instructions
Default username: admin TP-LINK router default password list
Default password: admin
Default subnet mask: 255.255.255.0
Default DNS server: 192.168.0.1
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 TL-WR850N v1 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://192.168.0.1
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 TP-LINK credentials, as they can usually be shared across models/variants.

TL-WR850N v1 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 TP-LINK TL-WR850N v1:

Flashing OpenWrt on the TP-LINK TL-WR850N v1

The TP-LINK TL-WR850N v1 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 TP-LINK TL-WR850N v1, 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.

TP-LINK stock firmware for the TL-WR850N v1

Stock firmwares for the TL-WR850N v1 are available under the download section on the modem's support page. You can also refer to the router's manual for instructions on how to upgrade the firmware.