FTP error 56

I’ve recently started intermittently getting error response code 56 while using sendsync to post data to an FTP. Anyone familiar with curl codes:
56:failure with receiving network data.
Could it be related to the server being slow and the EI agent giving up trying to post because of a delayed response?

It could be. If you PM us with details we can always take a packet dump and see what’s going on in more detail.

Thanks @Hugo I’ve pm’d you with the details of devices that are doing this. We have weather stations that have been posting to an ftp every 10 minutes, and just started getting this error a few days ago. I noticed if I posted some stations just after (eg 10:02, 10:12…) instead of (10:00, 10:10…) the ftp attempts were more successful. Not sure if it’s due to the ftp server having slowed down, or something on the EI agent side.

Is the ftp server under your control? We do notice that when people start running many devices at once with synchronized posting of data, this obviously generates load peaks on servers and (eg) we see things like data.sparkfun.com get all upset on the obvious time boundaries (:00, :15, :30, :45) but it’s just fine between these - looking in aggregate over the many tens of millions of requests we make outbound to these services daily.

I doubt it’s on our side but I’ll be checking the details in your PM later and coming up with a conclusive answer.