Our best guess is this: yesterday the CDN that we use had an outage- its "DNS" server was down. Some internet providers cache those records, so I'm guessing yours cached the bad DNS values when it was down. You need to flush those values from your computer so that they refresh to the new, correct, values.
This is only a guess, but it fits all the evidence we're seeing because most players can play fine, but a few cannot. Some internet providers update their DNS a lot.
Here's how to flush and refresh the DNS values:
If you are NOT on Windows 10: Go to Start, Run and enter “cmd”. If you are on Windows 10: open the start menu, immediately type "cmd" and click "Command Prompt" that appears in the list
Type “ipconfig /flushdns” into the command prompt.
Press Enter. You will be informed that your DNS cache has been cleared.
If you experience problems refreshing the cache you could also try the following commands in the stated order(press enter after each command):