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