VDSL Modem with AIS Fiber in Thailand, offers a "custom" setup but I can't succeed to make it work.

Thanks

Could you please post the settings of your router's custom option here so that we may further assist you?

It took me some time, but here I am :-) with the same modem/router and still can't find the automatic way.

I would try the below settings:

DNS server: api.dynu.com
Hostname: your Dynu hostname
Username: Dynu account username
Password: Dynu account password

Looks like a simple settings. But you never know if it would work or not. Some of the routers have some special protocols and they do not provide enough information for you to configure it.

How to Add Port Numbers to be used in Port Forwarding, Thanks to advise.