It appears that the 3 red builds you had nothing to do with the sync servers. They are red in the ‘Build’ job, task ‘Build and push docker image’, specifically when pushing the image to dockerhub. All three red builds ran in the ‘yak’ agent.
So the question is: was yak broken or dockerhub had some problems? Hard to tell. We can see that yak was able to push a new image, so I assume the problem was solved. And most likely than not, the problem was dockerhub.
It’s a little bit hard to guess what happens unless we follow the logs.