Running a suite of Automated Test jobs, we have started getting the Salesforce message 'Check your internet connection and try again' at apparently random stages.
 
There's no evidence on our server that there's a problem with the internet connectivity and we don't get the error when going into Salesforce front end and reproducing what the Auto Test is doing. We have tried running the tests on a different Salesforce Org/Instance, but the problem is the same.
 
Although it's not impossible that the internet connection could be dropping out intermittently, I'm wondering if it is an accurate message or if the root cause is something else. Has anyone seen this message and if so what can be done to resolve it?
 

I'm doing the simple lightning components challenge and have hit this problem in my existing trailhead org and a brand new dev org that I've just created:

Challenge not yet complete... here's what's wrong: 
There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: QVWBQHAG