After taking a look in your account, it looks as if you solved the issue and were able to take the exam. Could you give us an update on what the issue was, in case others encounter the issue and find this post?
I am having the same issue with this. I've install a new copy of the virtual tester and still get the same error message. Can you please let us know what the remedy was to this?
Yes I solved this issue myself in the end. I used to use an Ethernet in my university long time ago and I noticed that those proxy settings were still active in my computer settings for some reason (even though I was trying to connect VirtualTester server from home wifi). However every time I tried to change the LAN settings to "automatically detect settings", they switched back to the university proxy settings by them selves. After disabling my Webroot antivirus I was able to get rid of the uni proxy settings for good. Seems that the antivirus was permitting any changes to be made to proxy settings.
If you are having similar issues it might be worth checking your proxy settings. Access to those settings is instructed here: How to Enter Proxy Settings in Internet Explorer: 9 Steps
The university proxy settings were clearly blocking my computer from connecting to VirtualTester server in my home wifi. When I managed to get rid of these settings I was able to connect without issues.
According to my understanding proxy settings can be affected by malwares too.
Hope this helps.