>Because the third-party runners sit outside GitHub’s network, they rely on a direct IP link to reach GitHub. The provider traced the hangs to intermittent degradation on that link.

This is interesting. If I read that correctly this means the CI host had a direct peering connection with Github or Azure network.

Why were they not able solve the issue?

the blog mentions that they use a local cache to "reduce the time" but the problem is not solved right?