New guide. Old one is here https://forum.lowyat.net/topic/4202122
I'm sure you all will let me know if got any mistakes.

First post is only using terminal and command line.
Second post is using Quickset and a bit of command line.

I'm lazy to put screenshots. Maybe later.

Winbox
I suggest using Winbox to configure your Mikrotik router. Download from https://mikrotik.com/download
You can also SSH to the router or use the web configuration page which has a terminal.

Defaults
IP: 192.168.88.1
Username: admin
Password: blank

Ports
LAN port 1 (ether1) is your WAN port. (Connect modem here)
LAN Port 2-5 for your devices. Later we can use port 5 for UnifiTV.

Command Line Method

OK, let's go

Connect to the router using Winbox and open a New Terminal or use SSH. Change to your Unifi username and password first then copy and paste the commands below


Done. That's all you need for a very basic setup. Internet should be working now.
Explain a bit

First ensure IPv6 package is enabled. This is just to get the IPv6 firewall rules configured in case we want to setup IPv6 in the future.


Reset to default configuration. Very important. Router will be reboot.


When you reconnect, the router will ask you to change password.

Create VLAN 500.


Create PPPoE Client


Add PPPoE client to the WAN interface list


Enable UPNP. Not mandatory but many apps uses UPNP.


WiFi, UnifiTV & IPv6
Wait ya.