I had some issues with getting my NMC to accept a DHCP address. After much troubleshooting I found a way to make it work. I wrote it up on my Medium site and Nathan encouraged me to share it here. So if you are getting stuck with your card maybe this will help.
I admit, I did stop troubleshooting at the point of working so I dont actually know the root cause, so sorry if you want to know! But hopefully if you have the same issue it might be easier to fix with this!
https://medium.com/techielife/troubles-with-older-apc-and-dhcp-a-how-to-71c48fd7b997
Excellent work Nick - thank you for posting here and porviding the link. Cutomers - you can have a go fighting the DCHP beast as Nick did, and he beat it, or if you are stuck we can set a static IP for you - we need the card here to do that as we do it with a comms lead.