Lan port into Wan port on WR840N V4. Possible?

Hey guys.
My wan port on router tp link WR840N V4 suddenly stopped working.
Light doesn't get on and in network setting it shows "No cable connected to wan port.
So my WAN port stopped working.

Is it possible on this router to convert one of the LAN ports into WAN port?

usually, yes. The best way to do this is to look at the network config file and then make an edit to the way the ports are assigned.

Please copy the output of the following commands and post it here using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have:

cat /etc/config/network

I am actually new to do all this?
Where do i get network config file? from cmd?

yes, ssh into the router and issue the command on the command line.
On Mac/Linux, you can open a terminal window and type ssh root@<your.router.ip.address> (usually that router IP is if you're running a relatively default configuration). On Windows, you may want to use a program such as PuTTY.

Okay i just have installed Putty.
I am getting into it.

It is asking for a password and the password and username is defauly admin,admin.
But it can't write it there.

you first have to log in -- the username is root and the password is whatever you set (if you didn't set a password, it will be blank and will just log right in).

Username root
then it asks for password and i kept it empty and pressed enter but access denied.
Then i wrote admin as password but same access denied

the password is what you set on your device when you configured it. It will be the same as what you use when logging into the web interface.

Yes but i haven't set any password.
I just reset the router and it went back to default configuration.

and i can't write anything when it asks for password.

try this -- go to the router's web interface ( or See if you can login there (root, no password if you've just reset it).

I can login by username: admin & password: admin

you are not using OpenWrt. That is the vendor firmware.

My guess is that the TP-Link firmware does not allow you to make the change you're trying to implement. But you can ask TP-Link's support. Or you can install OpenWrt on your router:

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In order to convert LAN port into WAN port, i guess i have to install OpenWrt right?
Then i would install it.
Should i install it first?

I don't know if there is any way to do this with the TP-Link firmware, but it should be easy to do with OpenWrt.

Yes.... given that you need to use OpenWrt firmware to be able to change the physical port configurations, I'm not sure how you would do it if you don't install OpenWrt.

Yes, i am going to install OpenWrt first.

Which method i go for? kernel or TFTP recovery?

Instructions are here:

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Thanks i am on it.
Trying to install Openwrt.
I will let you know once it done.

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Sounds good.