521 errors are your origin server refusing the connection - so it’s something in your hosting provider’s network or on your server doing this. Take a look here for more details: Community Tip - Fixing Error 521: Web server is down
521 errors are your origin server refusing the connection - so it’s something in your hosting provider’s network or on your server doing this. Take a look here for more details: Community Tip - Fixing Error 521: Web server is down