Dahua NVR can be DHCP client and server at the same time.
As client - LAN port
As server for switches ports
These two networks must be in different network segment.
1. Dahua NVR supports FTP snapshots, check your configuration schedule.
2.Strange request.. for what you use FTP? You can record to HDD snapshot and get remote access via DSS or Smart-PSS
I tested IPC-HDBW4421F(-AS) 2.8mm IP67, IK10 that is okay. Good image, price.
Maybe better use dahua intercom, theretwo-way conversation, camera, like VTO6100C.
I think more useful.