Sounds like your AV, firewall or other security software kicking in and blocking the connection.
Any reason as to why it would just happen randomly though? I'm no expert by any means but it just seems weird that it would detect and block them only sometimes.
Well, thanks for the response. I'll try and look into it more and see if the AV actually blocks anything otherwise I'm at a loss.
try to uninstall it and see if that works.