Github is currently working for me via Hughesnet.
I tried the github-debug dot com diagnostics again, and these two errors still occurred, so I guess they are irrelevant.
Two errors that stood out to me were:
- The ssh git clone test also said "The authenticity of host '[github dot com]' (140...4) can't be established."
- A ping test from some github host to my ip address said "Destination Net Unreachable". [this was the 184.xx.xx.xx public ipv4 address which as MarkJFine pointed out, might not work from behind a NAT (network address translation) router, either hughesnet's or github's.]