We have video (mp4) files on the Google Storage with the CDN enabled. The videos are pseudo-streamed (HTTP byte-range) well from all but one of our users. All videos have same format, were encoded by ffmpeg with the same parameters. All videos are streamed well from different locations (especially tested from USA and Europe).
Just one user from South Korea reports he cannot stream some videos, but can stream the others well. He has tried 3 different devices (Windows, iPhone, Android tabled) with same result. He has tried to switch to mobile network (LTE) and still had the problem. We do not know if other users in South Korea have same problem or not, we have not many users there.
Is it possible the PoP or GCC nodes in the South Korea serve little different data than elsewhere? Is it possible to test HTTP requests to the same PoP, GCC nodes as the Korean users from Europe?
Update: After a few more test with the user we have found that the video downloaded (by
curl) is correct. He has problem with some fresh videos, too, so the problem is not in caching. The problem arises, when the video has index at the end, so the played has to seek to the end of file first (HTTP
byte-range). (But not always, he can play some videos with the index at the end).