error I/O "Error: Connection reset

Good morning,
I want to validate CCS in  https://jigsaw.w3.org/css-validator/ this URL https://servicioselectorales.tse.go.cr/PlataformaExterna but I've received this error :  "error I/O "Error: Connection reset".
Last week was working well, but right now it's not working. Please , let me know If you can help me , I'm really worried about this situation.
Regards,

Received on Monday, 6 July 2015 20:16:52 UTC