ERR_CERT_COMMON_NAME_INVALID

For some reason, I can't get to our Github using Chrome, it is reporting an insecure connection with the error ERR_CERT_COMMON_NAME_INVALID. This seems like a crap error, and the admin of our github likes fancy linux tricks one of which may have caused this problem, or the problem might be with Chrome.

Here is a nice page on how to check if the problem is Chrome. So far the first few hints haven't worked but I'm only halfway through the list: https://www.xtremerain.com/fix-err-cert-common-name-invalid/