I have three Netvanta 1238PoE switches running our VoIP environment, they are Generation 1 switches part number 1700599G1, they are all VLAN1 and are interconnected. I have a physical DHCP server connected to one of the switches and that's where the phones get their IP from, I was recently asked to move the DHCP scope to our AD server which is on another subnet, I have looked into dhcp relay however it does not seem to be available for the current OS I have which is 9700594-2A180101.biz, do you know which version supports DHCP relay?
The last version for that switch is 18.01.08 from 2015. You're running 18.01.01. Release notes for 18.01.08 don't show any added features so you may be out of luck with DHCP relay. You could configure the AD server's port as a trunk and pass both subnets to it on VLANs so that it has a presence on the VoIP subnet.
We put our DHCP relay statements on the core router between subnets. I would not think it mattered what firmware the switch had.