Unable to Set Redirection: must be a valid IP or domain

I get the error “The IP Address/FQDN for PBX must be a valid IP or domain” when trying to set the redirection to an FQDN that is only valid within my network. The Sangoma portal refuses to save the settings and so I cannot deploy my S305 phones.

The FQDN is valid within my network and takes this form: pbx-hostname.internal-domain.com

I’m aware that internal domains should not use TLDs but I cannot change it.

How can I get around this problem? I want the phones to use HTTPS to the DNS record instead of the IP.

Open a support ticket with the actual fqdn you are using.