iPad DNS issue

Hi.

I have an iPad issue that is frustrating me somewhat. I have a windows 8.1 virtual machine that is accessed by a VNC server running on the machine so visitors can use their devices as physical hardware to operate a work machine. This machine has a host name set up in the DNS page of our Cisco router and all works lovely on Windows PCs and Android, however iPads won't connect with VNC Viewer giving an error "The computer's domain name could not be resolved.". If I give an iPad a static IP address, subnet, router IP and DNS IP it will connect using the host name without any issues.

All the addresses are the same regardless of whether I am using a DHCP assigned setup or Static. Does anyone know why the static configuration works when the DHCP one doesn't, even though the settings are the same in each? Is this a software bug?