I had this error too. My domian name was a subdomain like xxx.yyy.com
And cpanel ftp configuration guided me that ftp server is ftp.xxx.yyy.com
Fillzilla was unable to connect and showed this error:
Connection attempt failed with “EAI_NONAME – Neither nodename nor
servname provided, or not known”.
This error is for dns resolving. I just removed “ftp.” from ftp.xxx.yyy.com and it works now
Remove “ftp.” from HOST name. e.g. if your website is http://www.example.com & you are using “ftp.example.com” then try with “example.com” only as host name…. it simply worked with me!