This issue seems familiar. So I dug up this old topic which I think applies here too:
So I think the same issue applies here: you are on an IPv6-only connection, our hosting platform is IPv4 only, your internet provider (presumably) is operating an IPv6-to-IPv4 gateway, and this gateway is mucking up the FTP connection.
Here are a few things you could try:
- Change the FTP mode in FileZilla from Passive to Active (or the other way around).
- Use a VPN (preferably one with IPv4 connectivity).