Hello,
What Linux distribution are you using?
I have quite a few Dell PowerEdge servers myself and I remember I had a similar problem with one or two of them.
I assume the network card does not appear when using tools like "ip link" or "ifconfig".
The most likely cause is missing network card firmware; quite a few network card models require the kernel to load the firmware into them. You will probably have to install the missing firmware package.
Regarding the application errors it is probably due to a missing package which also needs to be installed. This installation process will be different based on which distro you are using.
Thank you for your time!
Best wishes,
Ionut