Invalid hostname - components cannot be all number

[louisjeck]

Hello,
FileZilla refuses hostnames like ftp.1234.com when generating certificates (self signed or let's encrypt).
An error is shown

Invalid hostname 'ftp.1234.com'.
Components of host names cannot be all numbers.

According to RFC1123 these hostnames are valid, and shouldn't be blocked for certificate generation.

[Fabio Alemagna]

Thanks for reporting. The issue has been solved and the fix will be available in the next release and next nightly build.