Please use a valid hostname according to RFC1178 when trying to add a .co domain

Hi, I’m trying to install Hestia on a fresh Debian 11 install.

When asked for a FQDN I add my domain but I receive the error “Please use a valid hostname according to RFC1178”

My domain is a .co - is there a way round this? I want to access Hestia from my domain.

Use hostname.domain.com