you was probably able to get Stadia, because it's available and working in Germany. But now that you moved to Thailand, it's not supported anymore so that might be a reason, why it's not working properly for you. Just to be sure, you could also of course ask the Stadia support if there is anything you can do regarding this.
Stadia and the Stadia Controller are available in the following regions:
At this time, Stadia is not supported in Hawaii or Guam. Puerto Rico and Alaska are supported. Source: This article
Hey man, this is an unofficial workaround and it is not guaranteed to work, but at least it is something you could use before they start supporting Stadia in Thailand. I play with many friends from unsupported regions and this is working for them.
I hope this helped!