We're seeing reports that Steam Store has been blocked in Viet Nam. It appears to not resolve when using DNS provided by ISPs, and some IPs are being blocked directly.
https://sh.itjust.works/pictrs/image/df5f3b5f-d916-462d-9226-82ad679b835a.png
https://sh.itjust.works/pictrs/image/df5f3b5f-d916-462d-9226-82ad679b835a.png