Whenever I logged into the router setup page, I found an option for configuring
radius server. But didn’t try anytime. and no more! Let’s try out.

Update apt cache

sudo bash
apt-get update

apt-get install freeradius -y

Edit /etc/freeradius/clients.conf

sudo nano /etc/freeradius/clients.conf

Add a new client

client  0.0.0.0/0 {
secret          = {RADIUS shared key}
shortname       = any
}

Edit /etc/freeradius/users

sudo nano /etc/freeradius/users

Add a new user to file

testuser Cleartext-password :="password"

Restart the service

service freeradius restart

For more details: https://wiki.freeradius.org/guide/Getting%20Started#installing-the-server

That’s it. Now we need to configure radius server on our router.
If you use it on a regular basis, You will want to allocate a
static ip to the device running the radius server

The FreeRadius server runs on port 1812

Now we can connect to our router with username and the password we had set.