Hi Khun Toy,
I’ve worked a lot with Mikrotik. They are very stable. I can bring a Mikrotik for you to test if you like?
With the setup in your link below the Mikrotik will have a 192.168.0 IP on its WAN port and another IP range on its LAN port (maybe 10.0.0.x).
The Mikrotik will use DHCP and NAT.
This setup can be achieved with any wireless router, It doesn’t have to be Mikrotik