Friday morning I used VST Connect and it worked great.
I am running VST Connect Performer and the other person is on Cubase running VST Connect Pro.
Today we have tried connecting with the same project with the same settings but the result is:
"Connection Error"
Sorry, connection failed! Make sure both sides use the same up-to-date version!"
And yes, we are running the same version. 
Is Steinberg having server problems or is something else up?
hi - are you sure they are the same version - click on the Steinberg logo just to double check - this gives the ‘about’ page.
(I know 
…but it wouldn’t be first time )
That message is mandatory, in some cases at least one side can provide a message like „the other side is using an incompatible version“, in other cases neither side can know if a version mismatch could be the culprit.
There was a short period of possible lesser connectivity last Friday, but all is running well again. Does the problem still persist?
Super sure. We double checked. None of us had changed a thing since the latest 5h friday session.
Today we even downloaded the latest version just to be sure and installed again.
Problem persisted.
I got hold of the other party just now and we did a brief test and now it works again without any changes made.
With other words it was a service malfunction.
Somewhat annoying since it was a paid session and now there’s no time for a new session until next week.
Feels a bit scary that you can’t trust the service. 
Really sorry about that. Will try everything to make sure it won’t happen again.
Pls note that this is an extra service though, which helps in the case where a peer-to-peer connection is blocked by a firewall.
We’re also looking into new ways to allow for even safer connections.