I’ve recently stumbled upon this issue too. I found none of the solutions I found within the first Google searches to be of no use, but luckily found a solution of my own…
In Site Manager change Encryption to “Only use plain FTP”, mine were previously “Use explicit FTP over TLS if available”.
FYI, the previous fixes I tried were:
- Firewall configuration on the router – not possible due to work network and found is was only my PC.
- Change something on Remote server to do with ports – Again, not possible and was only my PC having the fault.
- Switching Filezilla from Passive to Active – Didn’t work
- Using SSH instead – rejected