Hello,
a cURL error 55 means that the connection between the two machines has been reset, it could be in either directions: the remote server is refusing connections because too much data has been received or your server firewall blocked it.
Sadly, that's not easy to troubleshoot, since it happens from outside the "web" environment. What you can do is to try to play with the part size, maybe the problem is the amount of connections opened in a short amount of time and not the total amount of data. If you increase it, fewer transfers are required and maybe you can stay under the threshold.
Davide Tampellini
Developer and Support Staff
🇮🇹Italian: native 🇬🇧English: good • 🕐 My time zone is Europe / Rome (UTC +1)
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!