Intermittent network timeout in docker
Solution 1:
The issue was related to MTU. Our cluster is using Calico VXLAN networking, which has an MTU of 1450. The inner Docker container wasn't taking cognizance of this and it doesn't seem to have been picked up during the path MTU discovery (PMTUD). Weirdly enough, this was a problem with the Fastly CDN, and not other server hosts that I tried, so that was an additional confounding factor. The issue went away when I set the MTU for the inner Docker containers to 1450 as well.