while many things can factor into a websites connection it is possible the servers got an issue.
but then you mentioned 2 servers that had issues. x11 and x15.
i am on x15 and never noticed a problem. but then i do not use uptime to check my free website.
im not sure but you should make sure running uptime every 5 minutes is a good idea.
compared to just a few times per day. this may show an increase in connections.